diff --git a/makefile b/makefile
index 72a06bc..7dbc143 100644
--- a/makefile
+++ b/makefile
@@ -1,560 +1,63 @@
-# Helpful Links
-
-# http://clarkgrubb.com/makefile-style-guide
-# https://explainshell.com
-# https://stackoverflow.com/questions/448910
-# https://shiroyasha.svbtle.com/escape-sequences-a-quick-guide-1
-
-SHELL := /bin/bash
-.SHELLFLAGS := -O extglob -eo pipefail -c
-.DEFAULT_GOAL := help
-.SUFFIXES:
-
--include makefile.config.make
-
-PROJECT_DIR := $(notdir $(abspath .))
-
-ifndef DEVELOPMENT_PYTHON_VERSION
-	DEVELOPMENT_PYTHON_VERSION := python=3.6
-endif
-
-ifndef SUPPORTED_PYTHON_VERSIONS
-	SUPPORTED_PYTHON_VERSIONS := $(DEVELOPMENT_PYTHON_VERSION)
-endif
-
-PKG_NAME := $(PACKAGE_NAME)
-
-# TODO (mb 2018-09-23): Support for bash on windows
-#    perhaps we need to install conda using this
-#    https://repo.continuum.io/miniconda/Miniconda3-latest-Windows-x86_64.exe
-PLATFORM = $(shell uname -s)
-
-# miniconda is shared between projects
-CONDA_ROOT := $(shell if [[ -d /opt/conda/envs ]]; then echo "/opt/conda"; else echo "$$HOME/miniconda3"; fi;)
-CONDA_BIN := $(CONDA_ROOT)/bin/conda
-
-ENV_PREFIX := $(CONDA_ROOT)/envs
-
-DEV_ENV_NAME := \
-	$(subst pypy,$(PKG_NAME)_pypy,$(subst python=,$(PKG_NAME)_py,$(subst .,,$(DEVELOPMENT_PYTHON_VERSION))))
-
-CONDA_ENV_NAMES := \
-	$(subst pypy,$(PKG_NAME)_pypy,$(subst python=,$(PKG_NAME)_py,$(subst .,,$(SUPPORTED_PYTHON_VERSIONS))))
-
-CONDA_ENV_PATHS := \
-	$(subst pypy,$(ENV_PREFIX)/$(PKG_NAME)_pypy,$(subst python=,$(ENV_PREFIX)/$(PKG_NAME)_py,$(subst .,,$(SUPPORTED_PYTHON_VERSIONS))))
-
-# envname/bin/python is unfortunately not always the correct
-# interpreter. In the case of pypy it is either envname/bin/pypy or
-# envname/bin/pypy3
-CONDA_ENV_BIN_PYTHON_PATHS := \
-	$(shell echo "$(CONDA_ENV_PATHS)" \
-	| sed 's!\(_py[[:digit:]]\+\)!\1/bin/python!g' \
-	| sed 's!\(_pypy2[[:digit:]]\)!\1/bin/pypy!g' \
-	| sed 's!\(_pypy3[[:digit:]]\)!\1/bin/pypy3!g' \
-)
-
-
-empty :=
-literal_space := $(empty) $(empty)
-
-BDIST_WHEEL_PYTHON_TAG := \
-	$(subst python,py,$(subst $(literal_space),.,$(subst .,,$(subst =,,$(SUPPORTED_PYTHON_VERSIONS)))))
-
-SDIST_FILE_CMD = ls -1t dist/*.tar.gz | head -n 1
-
-BDIST_WHEEL_FILE_CMD = ls -1t dist/*.whl | head -n 1
-
-
-# default version for development
-DEV_ENV := $(ENV_PREFIX)/$(DEV_ENV_NAME)
-DEV_ENV_PY := $(DEV_ENV)/bin/python
-
-RSA_KEY_PATH := $(HOME)/.ssh/$(PKG_NAME)_gitlab_runner_id_rsa
-
-DOCKER_BASE_IMAGE := registry.gitlab.com/mbarkhau/pycalver/base
-
-GIT_HEAD_REV = $(shell git rev-parse --short HEAD)
-DOCKER_IMAGE_VERSION = $(shell date -u +'%Y%m%dt%H%M%S')_$(GIT_HEAD_REV)
-
-MAX_LINE_LEN = $(shell grep 'max-line-length' setup.cfg | sed 's![^0-9]\{1,\}!!')
-
-
-build/envs.txt: requirements/conda.txt
-	@mkdir -p build/;
-
-	@if [[ ! -f $(CONDA_BIN) ]]; then \
-		echo "installing miniconda ..."; \
-		if [[ $(PLATFORM) == "Linux" ]]; then \
-			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh" \
-				> build/miniconda3.sh; \
-		elif [[ $(PLATFORM) == "MINGW64_NT-10.0" ]]; then \
-			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh" \
-				> build/miniconda3.sh; \
-		elif [[ $(PLATFORM) == "Darwin" ]]; then \
-			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-MacOSX-x86_64.sh" \
-				> build/miniconda3.sh; \
-		fi; \
-		bash build/miniconda3.sh -b -p $(CONDA_ROOT); \
-		rm build/miniconda3.sh; \
-	fi
-
-	rm -f build/envs.txt.tmp;
-
-	@SUPPORTED_PYTHON_VERSIONS="$(SUPPORTED_PYTHON_VERSIONS)" \
-		CONDA_ENV_NAMES="$(CONDA_ENV_NAMES)" \
-		CONDA_ENV_PATHS="$(CONDA_ENV_PATHS)" \
-		CONDA_ENV_BIN_PYTHON_PATHS="$(CONDA_ENV_BIN_PYTHON_PATHS)" \
-		CONDA_BIN="$(CONDA_BIN)" \
-		bash scripts/setup_conda_envs.sh;
-
-	$(CONDA_BIN) env list \
-		| grep $(PKG_NAME) \
-		| rev | cut -d " " -f1 \
-		| rev | sort >> build/envs.txt.tmp;
-
-	mv build/envs.txt.tmp build/envs.txt;
-
-
-build/deps.txt: build/envs.txt requirements/*.txt
-	@mkdir -p build/;
-
-	@SUPPORTED_PYTHON_VERSIONS="$(SUPPORTED_PYTHON_VERSIONS)" \
-		CONDA_ENV_NAMES="$(CONDA_ENV_NAMES)" \
-		CONDA_ENV_PATHS="$(CONDA_ENV_PATHS)" \
-		CONDA_ENV_BIN_PYTHON_PATHS="$(CONDA_ENV_BIN_PYTHON_PATHS)" \
-		CONDA_BIN="$(CONDA_BIN)" \
-		bash scripts/update_conda_env_deps.sh;
-
-	@echo "updating $(DEV_ENV_NAME) development deps ...";
-
-	@$(DEV_ENV_PY) -m pip install \
-		--disable-pip-version-check --upgrade \
-		--requirement=requirements/integration.txt;
-
-	@$(DEV_ENV_PY) -m pip install \
-		--disable-pip-version-check --upgrade \
-		--requirement=requirements/development.txt;
-
-	@echo "updating local vendor dep copies ...";
-
-	@$(DEV_ENV_PY) -m pip install \
-		--upgrade --disable-pip-version-check \
-		--no-deps --target=./vendor \
-		--requirement=requirements/vendor.txt;
-
-	@rm -f build/deps.txt.tmp;
-
-	@for env_py in $(CONDA_ENV_BIN_PYTHON_PATHS); do \
-		printf "\n# pip freeze for $${env_py}:\n" >> build/deps.txt.tmp; \
-		$${env_py} -m pip freeze >> build/deps.txt.tmp; \
-		printf "\n\n" >> build/deps.txt.tmp; \
-	done
-
-	@mv build/deps.txt.tmp build/deps.txt
-
-
-## Short help message for each task.
-.PHONY: help
-help:
-	@awk '{ \
-			if ($$0 ~ /^.PHONY: [a-zA-Z\-\_0-9]+$$/) { \
-				helpCommand = substr($$0, index($$0, ":") + 2); \
-				if (helpMessage) { \
-					printf "\033[36m%-20s\033[0m %s\n", \
-						helpCommand, helpMessage; \
-					helpMessage = ""; \
-				} \
-			} else if ($$0 ~ /^[a-zA-Z\-\_0-9.]+:/) { \
-				helpCommand = substr($$0, 0, index($$0, ":")); \
-				if (helpMessage) { \
-					printf "\033[36m%-20s\033[0m %s\n", \
-						helpCommand, helpMessage; \
-					helpMessage = ""; \
-				} \
-			} else if ($$0 ~ /^##/) { \
-				if (! (helpMessage)) { \
-					helpMessage = substr($$0, 3); \
-				} \
-			} else { \
-				if (helpMessage) { \
-					print "                     "helpMessage \
-				} \
-				helpMessage = ""; \
-			} \
-		}' \
-		$(MAKEFILE_LIST)
-
-	@if [[ ! -f $(DEV_ENV_PY) ]]; then \
-	echo "Missing python interpreter at $(DEV_ENV_PY) !"; \
-	echo "You problably want to install first:"; \
-	echo ""; \
-	echo "    make install"; \
-	echo ""; \
-	exit 0; \
-	fi
-
-	@if [[ ! -f $(CONDA_BIN) ]]; then \
-	echo "No conda installation found!"; \
-	echo "You problably want to install first:"; \
-	echo ""; \
-	echo "    make install"; \
-	echo ""; \
-	exit 0; \
-	fi
-
-
-## Full help message for each task.
-.PHONY: helpverbose
-helpverbose:
-	@printf "Available make targets for \033[97m$(PKG_NAME)\033[0m:\n";
-
-	@awk '{ \
-			if ($$0 ~ /^.PHONY: [a-zA-Z\-\_0-9]+$$/) { \
-				helpCommand = substr($$0, index($$0, ":") + 2); \
-				if (helpMessage) { \
-					printf "\033[36m%-20s\033[0m %s\n", \
-						helpCommand, helpMessage; \
-					helpMessage = ""; \
-				} \
-			} else if ($$0 ~ /^[a-zA-Z\-\_0-9.]+:/) { \
-				helpCommand = substr($$0, 0, index($$0, ":")); \
-				if (helpMessage) { \
-					printf "\033[36m%-20s\033[0m %s\n", \
-						helpCommand, helpMessage; \
-					helpMessage = ""; \
-				} \
-			} else if ($$0 ~ /^##/) { \
-				if (helpMessage) { \
-					helpMessage = helpMessage"\n                     "substr($$0, 3); \
-				} else { \
-					helpMessage = substr($$0, 3); \
-				} \
-			} else { \
-				if (helpMessage) { \
-					print "\n                     "helpMessage"\n" \
-				} \
-				helpMessage = ""; \
-			} \
-		}' \
-		$(MAKEFILE_LIST)
-
-
-## -- Project Setup --
-
-
-## Delete conda envs and cache 💩
-.PHONY: clean
-clean:
-	@for env_name in $(CONDA_ENV_NAMES); do \
-		env_py="$(ENV_PREFIX)/$${env_name}/bin/python"; \
-		if [[ -f $${env_py} ]]; then \
-			$(CONDA_BIN) env remove --name $${env_name} --yes; \
-		fi; \
-	done
-
-	rm -f build/envs.txt
-	rm -f build/deps.txt
-	rm -rf vendor/
-	rm -rf .mypy_cache/
-	rm -rf .pytest_cache/
-	rm -rf __pycache__/
-	rm -rf src/__pycache__/
-	rm -rf vendor/__pycache__/
-	@printf "\n setup/update completed  ✨ 🍰 ✨ \n\n"
-
-
-## Force update of dependencies by removing marker files
-##   Use this when you know an external dependency was
-##   updated, but that is not reflected in your
-##   requirements files.
-##
-##   Usage: make force update
-.PHONY: force
-force:
-	rm -f build/envs.txt
-	rm -f build/deps.txt
-	rm -rf vendor/
-	rm -rf .mypy_cache/
-	rm -rf .pytest_cache/
-	rm -rf __pycache__/
-	rm -rf src/__pycache__/
-	rm -rf vendor/__pycache__/
-
-
-## Setup python virtual environments
-.PHONY: install
-install: build/deps.txt
-
-
-## Update dependencies (pip install -U ...)
-.PHONY: update
-update: build/deps.txt
-
-
-## Install git pre-push hooks
-.PHONY: git_hooks
-git_hooks:
-	@rm -f "$(PWD)/.git/hooks/pre-push"
-	ln -s "$(PWD)/scripts/pre-push-hook.sh" "$(PWD)/.git/hooks/pre-push"
-
-
-## -- Integration --
-
-
-## Run flake8 linter
-.PHONY: lint
-lint:
-	@printf "flake8 ..\n"
-	@$(DEV_ENV)/bin/flake8 src/
-	@printf "\e[1F\e[9C ok\n"
-
-	@printf "sjfmt ..\n"
-	@$(DEV_ENV)/bin/sjfmt \
-		--target-version=py36 \
-		--skip-string-normalization \
-		--line-length=$(MAX_LINE_LEN) \
-		--check \
-		src/ test/ 2>&1 | sed "/All done/d" | sed "/left unchanged/d"
-	@printf "\e[1F\e[9C ok\n"
-
-
-## Run mypy type checker
-.PHONY: mypy
-mypy:
-	@rm -rf ".mypy_cache";
-
-	@printf "mypy ....\n"
-	@MYPYPATH=stubs/:vendor/ $(DEV_ENV_PY) -m mypy \
-		--html-report mypycov \
-		src/ | sed "/Generated HTML report/d"
-	@printf "\e[1F\e[9C ok\n"
-
-
-## Run pylint. Should not break the build yet
-.PHONY: pylint
-pylint:
-	@printf "pylint ..\n";
-	@$(DEV_ENV)/bin/pylint --jobs=4 --output-format=colorized --score=no \
-		 --disable=C0103,C0301,C0330,C0326,C0330,C0411,R0903,W1619,W1618,W1203 \
-		 --extension-pkg-whitelist=ujson,lxml,PIL,numpy,pandas,sklearn,pyblake2 \
-		 src/
-	@$(DEV_ENV)/bin/pylint --jobs=4 --output-format=colorized --score=no \
-		 --disable=C0103,C0111,C0301,C0330,C0326,C0330,C0411,R0903,W1619,W1618,W1203 \
-		 --extension-pkg-whitelist=ujson,lxml,PIL,numpy,pandas,sklearn,pyblake2 \
-		 test/
-
-	@printf "\e[1F\e[9C ok\n"
-
-
-## Run pytest unit and integration tests
-.PHONY: test
-test:
-	@rm -rf ".pytest_cache";
-	@rm -rf "src/__pycache__";
-	@rm -rf "test/__pycache__";
-
-	# First we test the local source tree using the dev environment
-	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
-		$(DEV_ENV_PY) -m pytest -v \
-		--doctest-modules \
-		--verbose \
-		--cov-report html \
-		--cov-report term \
-		$(shell cd src/ && ls -1 */__init__.py | awk '{ print "--cov "substr($$1,0,index($$1,"/")-1) }') \
-		test/ src/;
-
-	@rm -rf ".pytest_cache";
-	@rm -rf "src/__pycache__";
-	@rm -rf "test/__pycache__";
-
-
-## -- Helpers --
-
-
-## Run code formatter on src/ and test/
-.PHONY: fmt
-fmt:
-	@$(DEV_ENV)/bin/sjfmt \
-		--target-version=py36 \
-		--skip-string-normalization \
-		--line-length=$(MAX_LINE_LEN) \
-		 src/ test/
-
-
-## Shortcut for make fmt lint mypy test
-.PHONY: check
-check:  fmt lint mypy test
-
-
-## Start subshell with environ variables set.
-.PHONY: env_subshell
-env_subshell:
-	@bash --init-file <(echo '\
-		source $$HOME/.bashrc; \
-		source $(CONDA_ROOT)/etc/profile.d/conda.sh \
-		export ENV=$${ENV-dev}; \
-		export PYTHONPATH="src/:vendor/:$$PYTHONPATH"; \
-		conda activate $(DEV_ENV_NAME) \
-	')
-
-
-## Usage: "source ./activate", to deactivate: "deactivate"
-.PHONY: activate
-activate:
-	@echo 'source $(CONDA_ROOT)/etc/profile.d/conda.sh;'
-	@echo 'if [[ -z $$ENV ]]; then'
-	@echo '		export _env_before_activate=$${ENV};'
-	@echo 'fi'
-	@echo 'if [[ -z $$PYTHONPATH ]]; then'
-	@echo '		export _pythonpath_before_activate=$${PYTHONPATH};'
-	@echo 'fi'
-	@echo 'export ENV=$${ENV-dev};'
-	@echo 'export PYTHONPATH="src/:vendor/:$$PYTHONPATH";'
-	@echo 'conda activate $(DEV_ENV_NAME);'
-	@echo 'function deactivate {'
-	@echo '		if [[ -z $${_env_before_activate} ]]; then'
-	@echo '				export ENV=$${_env_before_activate}; '
-	@echo '		else'
-	@echo '				unset ENV;'
-	@echo '		fi'
-	@echo '		if [[ -z $${_pythonpath_before_activate} ]]; then'
-	@echo '				export PYTHONPATH=$${_pythonpath_before_activate}; '
-	@echo '		else'
-	@echo '				unset PYTHONPATH;'
-	@echo '		fi'
-	@echo '		conda deactivate;'
-	@echo '};'
-
-
-## Drop into an ipython shell with correct env variables set
-.PHONY: ipy
-ipy:
-	@ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
-		$(DEV_ENV)/bin/ipython
-
-
-## Like `make test`, but with debug parameters
-.PHONY: devtest
-devtest:
-	@rm -rf "src/__pycache__";
-	@rm -rf "test/__pycache__";
-
-ifdef FILTER
-	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
-		$(DEV_ENV_PY) -m pytest -v \
-		--doctest-modules \
-		--no-cov \
-		--verbose \
-		--capture=no \
-		--exitfirst \
-		--failed-first \
-		-k $(FILTER) \
-		test/ src/;
-else
-	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
-		$(DEV_ENV_PY) -m pytest -v \
-		--doctest-modules \
-		--no-cov \
-		--verbose \
-		--capture=no \
-		--exitfirst \
-		--failed-first \
-		test/ src/;
-endif
-
-	@rm -rf "src/__pycache__";
-	@rm -rf "test/__pycache__";
-
-
-## Run `make lint mypy test` using docker
-.PHONY: citest
-citest:
-	docker build --file Dockerfile --tag tmp_citest_$(PKG_NAME) .
-	docker run --tty tmp_citest_$(PKG_NAME) make lint mypy test test_compat
-
-
-## -- Build/Deploy --
-
-
-# Generate Documentation
-# .PHONY: doc
-# doc:
-# 	echo "Not Implemented"
-
-
-## Freeze dependencies of the current development env.
-##   The requirements files this produces should be used
-##   in order to have reproducable builds, otherwise you
-##   should minimize the number of pinned versions in
-##   your requirements.
-.PHONY: freeze
-freeze:
-	$(DEV_ENV_PY) -m pip freeze \
-		> requirements/$(shell date -u +"%Y%m%dt%H%M%S")_freeze.txt
-
-
-## Bump Version number in all files
-.PHONY: bump_version
-bump_version:
-	$(DEV_ENV)/bin/pycalver bump;
-
-
-## Create python sdist and bdist_wheel files
-.PHONY: dist_build
-dist_build:
-	$(DEV_ENV_PY) setup.py sdist;
-	$(DEV_ENV_PY) setup.py bdist_wheel --python-tag=py2.py3;
-	@rm -rf src/*.egg-info
-
-
-## Upload sdist and bdist files to pypi
-.PHONY: dist_upload
-dist_upload:
-	@if [[ "1" != "1" ]]; then \
-		echo "FAILSAFE! Not publishing a private package."; \
-		echo "  To avoid this set IS_PUBLIC=1 in bootstrap.sh and run it."; \
-		exit 1; \
-	fi
-
-	$(DEV_ENV)/bin/twine check $$($(SDIST_FILE_CMD));
-	$(DEV_ENV)/bin/twine check $$($(BDIST_WHEEL_FILE_CMD));
-	$(DEV_ENV)/bin/twine upload $$($(SDIST_FILE_CMD)) $$($(BDIST_WHEEL_FILE_CMD));
-
-
-## bump_version dist_build dist_upload
-.PHONY: dist_publish
-dist_publish: bump_version dist_build dist_upload
-
-
-## Build docker images. Must be run when dependencies are added
-##   or updated. The main reasons this can fail are:
-##   1. No ssh key at $(HOME)/.ssh/$(PKG_NAME)_gitlab_runner_id_rsa
-##      (which is needed to install packages from private repos
-##      and is copied into a temp container during the build).
-##   2. Your docker daemon is not running
-##   3. You're using WSL and docker is not exposed on tcp://localhost:2375
-##   4. You're using WSL but didn't do export DOCKER_HOST="tcp://localhost:2375"
-.PHONY: docker_build
-docker_build:
-	@if [[ -f "$(RSA_KEY_PATH)" ]]; then \
-		docker build \
-			--build-arg SSH_PRIVATE_RSA_KEY="$$(cat '$(RSA_KEY_PATH)')" \
-			--file docker_base.Dockerfile \
-			--tag $(DOCKER_BASE_IMAGE):$(DOCKER_IMAGE_VERSION) \
-			--tag $(DOCKER_BASE_IMAGE) \
-			.; \
-	else \
-		docker build \
-			--file docker_base.Dockerfile \
-			--tag $(DOCKER_BASE_IMAGE):$(DOCKER_IMAGE_VERSION) \
-			--tag $(DOCKER_BASE_IMAGE) \
-			.; \
-	fi
-
-	docker push $(DOCKER_BASE_IMAGE)
 
+PACKAGE_NAME := pycalver
+
+# This is the python version that is used for:
+# - `make fmt`
+# - `make ipy`
+# - `make lint`
+# - `make devtest`
+DEVELOPMENT_PYTHON_VERSION := python=3.7
+
+# These must be valid (space separated) conda package names.
+# A separate conda environment will be created for each of these.
+#
+# Some valid options are:
+# - python=2.7
+# - python=3.5
+# - python=3.6
+# - python=3.7
+# - pypy2.7
+# - pypy3.5
+SUPPORTED_PYTHON_VERSIONS := python=2.7 python=3.5 python=3.6 python=3.7 pypy2.7 pypy3.5
+
+
+include makefile.bootstrapit.make
 
 ## -- Extra/Custom/Project Specific Tasks --
 
--include makefile.extra.make
+
+## Start the development http server in debug mode
+##    This is just to illustrate how to add your
+##    extra targets outside of the main makefile.
+.PHONY: serve
+serve:
+	echo "Not Implemented"
+
+
+COMPAT_TEST_FILES = $(shell ls -1 test/*.py 2>/dev/null | awk '{ printf " compat_"$$0 }')
+
+compat_test/%.py: test/%.py
+	@mkdir -p compat_test/;
+	$(DEV_ENV)/bin/lib3to6 $< > $@.tmp;
+	mv $@.tmp $@;
+
+
+## Run pytest integration tests
+.PHONY: test_compat
+test_compat: $(COMPAT_TEST_FILES)
+	rm -rf compat_test/fixtures;
+	mkdir -p compat_test/fixtures;
+	cp -R test/fixtures compat_test/
+
+	# install the package and run the test suite against it.
+	rm -rf build/test_wheel;
+	mkdir -p build/test_wheel;
+	$(DEV_ENV_PY) setup.py bdist_wheel --dist-dir build/test_wheel;
+
+	IFS=' ' read -r -a env_pys <<< "$(CONDA_ENV_BIN_PYTHON_PATHS)"; \
+	for i in $${!env_pys[@]}; do \
+		env_py=$${env_pys[i]}; \
+		$${env_py} -m pip install --upgrade build/test_wheel/*.whl; \
+		ENABLE_BACKTRACE=0 PYTHONPATH="" ENV=$${ENV-dev} \
+			$${env_py} -m pytest --verbose compat_test/; \
+	done;
diff --git a/makefile.bootstrapit.make b/makefile.bootstrapit.make
new file mode 100644
index 0000000..ae83fdf
--- /dev/null
+++ b/makefile.bootstrapit.make
@@ -0,0 +1,557 @@
+# Helpful Links
+
+# http://clarkgrubb.com/makefile-style-guide
+# https://explainshell.com
+# https://stackoverflow.com/questions/448910
+# https://shiroyasha.svbtle.com/escape-sequences-a-quick-guide-1
+
+SHELL := /bin/bash
+.SHELLFLAGS := -O extglob -eo pipefail -c
+.DEFAULT_GOAL := help
+.SUFFIXES:
+
+
+PROJECT_DIR := $(notdir $(abspath .))
+
+ifndef DEVELOPMENT_PYTHON_VERSION
+	DEVELOPMENT_PYTHON_VERSION := python=3.6
+endif
+
+ifndef SUPPORTED_PYTHON_VERSIONS
+	SUPPORTED_PYTHON_VERSIONS := $(DEVELOPMENT_PYTHON_VERSION)
+endif
+
+PKG_NAME := $(PACKAGE_NAME)
+
+# TODO (mb 2018-09-23): Support for bash on windows
+#    perhaps we need to install conda using this
+#    https://repo.continuum.io/miniconda/Miniconda3-latest-Windows-x86_64.exe
+PLATFORM = $(shell uname -s)
+
+# miniconda is shared between projects
+CONDA_ROOT := $(shell if [[ -d /opt/conda/envs ]]; then echo "/opt/conda"; else echo "$$HOME/miniconda3"; fi;)
+CONDA_BIN := $(CONDA_ROOT)/bin/conda
+
+ENV_PREFIX := $(CONDA_ROOT)/envs
+
+DEV_ENV_NAME := \
+	$(subst pypy,$(PKG_NAME)_pypy,$(subst python=,$(PKG_NAME)_py,$(subst .,,$(DEVELOPMENT_PYTHON_VERSION))))
+
+CONDA_ENV_NAMES := \
+	$(subst pypy,$(PKG_NAME)_pypy,$(subst python=,$(PKG_NAME)_py,$(subst .,,$(SUPPORTED_PYTHON_VERSIONS))))
+
+CONDA_ENV_PATHS := \
+	$(subst pypy,$(ENV_PREFIX)/$(PKG_NAME)_pypy,$(subst python=,$(ENV_PREFIX)/$(PKG_NAME)_py,$(subst .,,$(SUPPORTED_PYTHON_VERSIONS))))
+
+# envname/bin/python is unfortunately not always the correct
+# interpreter. In the case of pypy it is either envname/bin/pypy or
+# envname/bin/pypy3
+CONDA_ENV_BIN_PYTHON_PATHS := \
+	$(shell echo "$(CONDA_ENV_PATHS)" \
+	| sed 's!\(_py[[:digit:]]\+\)!\1/bin/python!g' \
+	| sed 's!\(_pypy2[[:digit:]]\)!\1/bin/pypy!g' \
+	| sed 's!\(_pypy3[[:digit:]]\)!\1/bin/pypy3!g' \
+)
+
+
+empty :=
+literal_space := $(empty) $(empty)
+
+BDIST_WHEEL_PYTHON_TAG := \
+	$(subst python,py,$(subst $(literal_space),.,$(subst .,,$(subst =,,$(SUPPORTED_PYTHON_VERSIONS)))))
+
+SDIST_FILE_CMD = ls -1t dist/*.tar.gz | head -n 1
+
+BDIST_WHEEL_FILE_CMD = ls -1t dist/*.whl | head -n 1
+
+
+# default version for development
+DEV_ENV := $(ENV_PREFIX)/$(DEV_ENV_NAME)
+DEV_ENV_PY := $(DEV_ENV)/bin/python
+
+RSA_KEY_PATH := $(HOME)/.ssh/$(PKG_NAME)_gitlab_runner_id_rsa
+
+DOCKER_BASE_IMAGE := registry.gitlab.com/mbarkhau/pycalver/base
+
+GIT_HEAD_REV = $(shell git rev-parse --short HEAD)
+DOCKER_IMAGE_VERSION = $(shell date -u +'%Y%m%dt%H%M%S')_$(GIT_HEAD_REV)
+
+MAX_LINE_LEN = $(shell grep 'max-line-length' setup.cfg | sed 's![^0-9]\{1,\}!!')
+
+
+build/envs.txt: requirements/conda.txt
+	@mkdir -p build/;
+
+	@if [[ ! -f $(CONDA_BIN) ]]; then \
+		echo "installing miniconda ..."; \
+		if [[ $(PLATFORM) == "Linux" ]]; then \
+			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh" \
+				> build/miniconda3.sh; \
+		elif [[ $(PLATFORM) == "MINGW64_NT-10.0" ]]; then \
+			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh" \
+				> build/miniconda3.sh; \
+		elif [[ $(PLATFORM) == "Darwin" ]]; then \
+			curl "https://repo.continuum.io/miniconda/Miniconda3-latest-MacOSX-x86_64.sh" \
+				> build/miniconda3.sh; \
+		fi; \
+		bash build/miniconda3.sh -b -p $(CONDA_ROOT); \
+		rm build/miniconda3.sh; \
+	fi
+
+	rm -f build/envs.txt.tmp;
+
+	@SUPPORTED_PYTHON_VERSIONS="$(SUPPORTED_PYTHON_VERSIONS)" \
+		CONDA_ENV_NAMES="$(CONDA_ENV_NAMES)" \
+		CONDA_ENV_PATHS="$(CONDA_ENV_PATHS)" \
+		CONDA_ENV_BIN_PYTHON_PATHS="$(CONDA_ENV_BIN_PYTHON_PATHS)" \
+		CONDA_BIN="$(CONDA_BIN)" \
+		bash scripts/setup_conda_envs.sh;
+
+	$(CONDA_BIN) env list \
+		| grep $(PKG_NAME) \
+		| rev | cut -d " " -f1 \
+		| rev | sort >> build/envs.txt.tmp;
+
+	mv build/envs.txt.tmp build/envs.txt;
+
+
+build/deps.txt: build/envs.txt requirements/*.txt
+	@mkdir -p build/;
+
+	@SUPPORTED_PYTHON_VERSIONS="$(SUPPORTED_PYTHON_VERSIONS)" \
+		CONDA_ENV_NAMES="$(CONDA_ENV_NAMES)" \
+		CONDA_ENV_PATHS="$(CONDA_ENV_PATHS)" \
+		CONDA_ENV_BIN_PYTHON_PATHS="$(CONDA_ENV_BIN_PYTHON_PATHS)" \
+		CONDA_BIN="$(CONDA_BIN)" \
+		bash scripts/update_conda_env_deps.sh;
+
+	@echo "updating $(DEV_ENV_NAME) development deps ...";
+
+	@$(DEV_ENV_PY) -m pip install \
+		--disable-pip-version-check --upgrade \
+		--requirement=requirements/integration.txt;
+
+	@$(DEV_ENV_PY) -m pip install \
+		--disable-pip-version-check --upgrade \
+		--requirement=requirements/development.txt;
+
+	@echo "updating local vendor dep copies ...";
+
+	@$(DEV_ENV_PY) -m pip install \
+		--upgrade --disable-pip-version-check \
+		--no-deps --target=./vendor \
+		--requirement=requirements/vendor.txt;
+
+	@rm -f build/deps.txt.tmp;
+
+	@for env_py in $(CONDA_ENV_BIN_PYTHON_PATHS); do \
+		printf "\n# pip freeze for $${env_py}:\n" >> build/deps.txt.tmp; \
+		$${env_py} -m pip freeze >> build/deps.txt.tmp; \
+		printf "\n\n" >> build/deps.txt.tmp; \
+	done
+
+	@mv build/deps.txt.tmp build/deps.txt
+
+
+## Short help message for each task.
+.PHONY: help
+help:
+	@awk '{ \
+			if ($$0 ~ /^.PHONY: [a-zA-Z\-\_0-9]+$$/) { \
+				helpCommand = substr($$0, index($$0, ":") + 2); \
+				if (helpMessage) { \
+					printf "\033[36m%-20s\033[0m %s\n", \
+						helpCommand, helpMessage; \
+					helpMessage = ""; \
+				} \
+			} else if ($$0 ~ /^[a-zA-Z\-\_0-9.]+:/) { \
+				helpCommand = substr($$0, 0, index($$0, ":")); \
+				if (helpMessage) { \
+					printf "\033[36m%-20s\033[0m %s\n", \
+						helpCommand, helpMessage; \
+					helpMessage = ""; \
+				} \
+			} else if ($$0 ~ /^##/) { \
+				if (! (helpMessage)) { \
+					helpMessage = substr($$0, 3); \
+				} \
+			} else { \
+				if (helpMessage) { \
+					print "                     "helpMessage \
+				} \
+				helpMessage = ""; \
+			} \
+		}' \
+		$(MAKEFILE_LIST)
+
+	@if [[ ! -f $(DEV_ENV_PY) ]]; then \
+	echo "Missing python interpreter at $(DEV_ENV_PY) !"; \
+	echo "You problably want to install first:"; \
+	echo ""; \
+	echo "    make install"; \
+	echo ""; \
+	exit 0; \
+	fi
+
+	@if [[ ! -f $(CONDA_BIN) ]]; then \
+	echo "No conda installation found!"; \
+	echo "You problably want to install first:"; \
+	echo ""; \
+	echo "    make install"; \
+	echo ""; \
+	exit 0; \
+	fi
+
+
+## Full help message for each task.
+.PHONY: helpverbose
+helpverbose:
+	@printf "Available make targets for \033[97m$(PKG_NAME)\033[0m:\n";
+
+	@awk '{ \
+			if ($$0 ~ /^.PHONY: [a-zA-Z\-\_0-9]+$$/) { \
+				helpCommand = substr($$0, index($$0, ":") + 2); \
+				if (helpMessage) { \
+					printf "\033[36m%-20s\033[0m %s\n", \
+						helpCommand, helpMessage; \
+					helpMessage = ""; \
+				} \
+			} else if ($$0 ~ /^[a-zA-Z\-\_0-9.]+:/) { \
+				helpCommand = substr($$0, 0, index($$0, ":")); \
+				if (helpMessage) { \
+					printf "\033[36m%-20s\033[0m %s\n", \
+						helpCommand, helpMessage; \
+					helpMessage = ""; \
+				} \
+			} else if ($$0 ~ /^##/) { \
+				if (helpMessage) { \
+					helpMessage = helpMessage"\n                     "substr($$0, 3); \
+				} else { \
+					helpMessage = substr($$0, 3); \
+				} \
+			} else { \
+				if (helpMessage) { \
+					print "\n                     "helpMessage"\n" \
+				} \
+				helpMessage = ""; \
+			} \
+		}' \
+		$(MAKEFILE_LIST)
+
+
+## -- Project Setup --
+
+
+## Delete conda envs and cache 💩
+.PHONY: clean
+clean:
+	@for env_name in $(CONDA_ENV_NAMES); do \
+		env_py="$(ENV_PREFIX)/$${env_name}/bin/python"; \
+		if [[ -f $${env_py} ]]; then \
+			$(CONDA_BIN) env remove --name $${env_name} --yes; \
+		fi; \
+	done
+
+	rm -f build/envs.txt
+	rm -f build/deps.txt
+	rm -rf vendor/
+	rm -rf .mypy_cache/
+	rm -rf .pytest_cache/
+	rm -rf __pycache__/
+	rm -rf src/__pycache__/
+	rm -rf vendor/__pycache__/
+	@printf "\n setup/update completed  ✨ 🍰 ✨ \n\n"
+
+
+## Force update of dependencies by removing marker files
+##   Use this when you know an external dependency was
+##   updated, but that is not reflected in your
+##   requirements files.
+##
+##   Usage: make force update
+.PHONY: force
+force:
+	rm -f build/envs.txt
+	rm -f build/deps.txt
+	rm -rf vendor/
+	rm -rf .mypy_cache/
+	rm -rf .pytest_cache/
+	rm -rf __pycache__/
+	rm -rf src/__pycache__/
+	rm -rf vendor/__pycache__/
+
+
+## Setup python virtual environments
+.PHONY: install
+install: build/deps.txt
+
+
+## Update dependencies (pip install -U ...)
+.PHONY: update
+update: build/deps.txt
+
+
+## Install git pre-push hooks
+.PHONY: git_hooks
+git_hooks:
+	@rm -f "$(PWD)/.git/hooks/pre-push"
+	ln -s "$(PWD)/scripts/pre-push-hook.sh" "$(PWD)/.git/hooks/pre-push"
+
+
+## -- Integration --
+
+
+## Run flake8 linter
+.PHONY: lint
+lint:
+	@printf "flake8 ..\n"
+	@$(DEV_ENV)/bin/flake8 src/
+	@printf "\e[1F\e[9C ok\n"
+
+	@printf "sjfmt ..\n"
+	@$(DEV_ENV)/bin/sjfmt \
+		--target-version=py36 \
+		--skip-string-normalization \
+		--line-length=$(MAX_LINE_LEN) \
+		--check \
+		src/ test/ 2>&1 | sed "/All done/d" | sed "/left unchanged/d"
+	@printf "\e[1F\e[9C ok\n"
+
+
+## Run mypy type checker
+.PHONY: mypy
+mypy:
+	@rm -rf ".mypy_cache";
+
+	@printf "mypy ....\n"
+	@MYPYPATH=stubs/:vendor/ $(DEV_ENV_PY) -m mypy \
+		--html-report mypycov \
+		src/ | sed "/Generated HTML report/d"
+	@printf "\e[1F\e[9C ok\n"
+
+
+## Run pylint. Should not break the build yet
+.PHONY: pylint
+pylint:
+	@printf "pylint ..\n";
+	@$(DEV_ENV)/bin/pylint --jobs=4 --output-format=colorized --score=no \
+		 --disable=C0103,C0301,C0330,C0326,C0330,C0411,R0903,W1619,W1618,W1203 \
+		 --extension-pkg-whitelist=ujson,lxml,PIL,numpy,pandas,sklearn,pyblake2 \
+		 src/
+	@$(DEV_ENV)/bin/pylint --jobs=4 --output-format=colorized --score=no \
+		 --disable=C0103,C0111,C0301,C0330,C0326,C0330,C0411,R0903,W1619,W1618,W1203 \
+		 --extension-pkg-whitelist=ujson,lxml,PIL,numpy,pandas,sklearn,pyblake2 \
+		 test/
+
+	@printf "\e[1F\e[9C ok\n"
+
+
+## Run pytest unit and integration tests
+.PHONY: test
+test:
+	@rm -rf ".pytest_cache";
+	@rm -rf "src/__pycache__";
+	@rm -rf "test/__pycache__";
+
+	# First we test the local source tree using the dev environment
+	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
+		$(DEV_ENV_PY) -m pytest -v \
+		--doctest-modules \
+		--verbose \
+		--cov-report html \
+		--cov-report term \
+		$(shell cd src/ && ls -1 */__init__.py | awk '{ print "--cov "substr($$1,0,index($$1,"/")-1) }') \
+		test/ src/;
+
+	@rm -rf ".pytest_cache";
+	@rm -rf "src/__pycache__";
+	@rm -rf "test/__pycache__";
+
+
+## -- Helpers --
+
+
+## Run code formatter on src/ and test/
+.PHONY: fmt
+fmt:
+	@$(DEV_ENV)/bin/sjfmt \
+		--target-version=py36 \
+		--skip-string-normalization \
+		--line-length=$(MAX_LINE_LEN) \
+		 src/ test/
+
+
+## Shortcut for make fmt lint mypy test
+.PHONY: check
+check:  fmt lint mypy test
+
+
+## Start subshell with environ variables set.
+.PHONY: env_subshell
+env_subshell:
+	@bash --init-file <(echo '\
+		source $$HOME/.bashrc; \
+		source $(CONDA_ROOT)/etc/profile.d/conda.sh \
+		export ENV=$${ENV-dev}; \
+		export PYTHONPATH="src/:vendor/:$$PYTHONPATH"; \
+		conda activate $(DEV_ENV_NAME) \
+	')
+
+
+## Usage: "source ./activate", to deactivate: "deactivate"
+.PHONY: activate
+activate:
+	@echo 'source $(CONDA_ROOT)/etc/profile.d/conda.sh;'
+	@echo 'if [[ -z $$ENV ]]; then'
+	@echo '		export _env_before_activate=$${ENV};'
+	@echo 'fi'
+	@echo 'if [[ -z $$PYTHONPATH ]]; then'
+	@echo '		export _pythonpath_before_activate=$${PYTHONPATH};'
+	@echo 'fi'
+	@echo 'export ENV=$${ENV-dev};'
+	@echo 'export PYTHONPATH="src/:vendor/:$$PYTHONPATH";'
+	@echo 'conda activate $(DEV_ENV_NAME);'
+	@echo 'function deactivate {'
+	@echo '		if [[ -z $${_env_before_activate} ]]; then'
+	@echo '				export ENV=$${_env_before_activate}; '
+	@echo '		else'
+	@echo '				unset ENV;'
+	@echo '		fi'
+	@echo '		if [[ -z $${_pythonpath_before_activate} ]]; then'
+	@echo '				export PYTHONPATH=$${_pythonpath_before_activate}; '
+	@echo '		else'
+	@echo '				unset PYTHONPATH;'
+	@echo '		fi'
+	@echo '		conda deactivate;'
+	@echo '};'
+
+
+## Drop into an ipython shell with correct env variables set
+.PHONY: ipy
+ipy:
+	@ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
+		$(DEV_ENV)/bin/ipython
+
+
+## Like `make test`, but with debug parameters
+.PHONY: devtest
+devtest:
+	@rm -rf "src/__pycache__";
+	@rm -rf "test/__pycache__";
+
+ifdef FILTER
+	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
+		$(DEV_ENV_PY) -m pytest -v \
+		--doctest-modules \
+		--no-cov \
+		--verbose \
+		--capture=no \
+		--exitfirst \
+		--failed-first \
+		-k $(FILTER) \
+		test/ src/;
+else
+	ENV=$${ENV-dev} PYTHONPATH=src/:vendor/:$$PYTHONPATH \
+		$(DEV_ENV_PY) -m pytest -v \
+		--doctest-modules \
+		--no-cov \
+		--verbose \
+		--capture=no \
+		--exitfirst \
+		--failed-first \
+		test/ src/;
+endif
+
+	@rm -rf "src/__pycache__";
+	@rm -rf "test/__pycache__";
+
+
+## Run `make lint mypy test` using docker
+.PHONY: citest
+citest:
+	docker build --file Dockerfile --tag tmp_citest_$(PKG_NAME) .
+	docker run --tty tmp_citest_$(PKG_NAME) make lint mypy test test_compat
+
+
+## -- Build/Deploy --
+
+
+# Generate Documentation
+# .PHONY: doc
+# doc:
+# 	echo "Not Implemented"
+
+
+## Freeze dependencies of the current development env.
+##   The requirements files this produces should be used
+##   in order to have reproducable builds, otherwise you
+##   should minimize the number of pinned versions in
+##   your requirements.
+.PHONY: freeze
+freeze:
+	$(DEV_ENV_PY) -m pip freeze \
+		> requirements/$(shell date -u +"%Y%m%dt%H%M%S")_freeze.txt
+
+
+## Bump Version number in all files
+.PHONY: bump_version
+bump_version:
+	$(DEV_ENV)/bin/pycalver bump;
+
+
+## Create python sdist and bdist_wheel files
+.PHONY: dist_build
+dist_build:
+	$(DEV_ENV_PY) setup.py sdist;
+	$(DEV_ENV_PY) setup.py bdist_wheel --python-tag=py2.py3;
+	@rm -rf src/*.egg-info
+
+
+## Upload sdist and bdist files to pypi
+.PHONY: dist_upload
+dist_upload:
+	@if [[ "1" != "1" ]]; then \
+		echo "FAILSAFE! Not publishing a private package."; \
+		echo "  To avoid this set IS_PUBLIC=1 in bootstrap.sh and run it."; \
+		exit 1; \
+	fi
+
+	$(DEV_ENV)/bin/twine check $$($(SDIST_FILE_CMD));
+	$(DEV_ENV)/bin/twine check $$($(BDIST_WHEEL_FILE_CMD));
+	$(DEV_ENV)/bin/twine upload $$($(SDIST_FILE_CMD)) $$($(BDIST_WHEEL_FILE_CMD));
+
+
+## bump_version dist_build dist_upload
+.PHONY: dist_publish
+dist_publish: bump_version dist_build dist_upload
+
+
+## Build docker images. Must be run when dependencies are added
+##   or updated. The main reasons this can fail are:
+##   1. No ssh key at $(HOME)/.ssh/$(PKG_NAME)_gitlab_runner_id_rsa
+##      (which is needed to install packages from private repos
+##      and is copied into a temp container during the build).
+##   2. Your docker daemon is not running
+##   3. You're using WSL and docker is not exposed on tcp://localhost:2375
+##   4. You're using WSL but didn't do export DOCKER_HOST="tcp://localhost:2375"
+.PHONY: docker_build
+docker_build:
+	@if [[ -f "$(RSA_KEY_PATH)" ]]; then \
+		docker build \
+			--build-arg SSH_PRIVATE_RSA_KEY="$$(cat '$(RSA_KEY_PATH)')" \
+			--file docker_base.Dockerfile \
+			--tag $(DOCKER_BASE_IMAGE):$(DOCKER_IMAGE_VERSION) \
+			--tag $(DOCKER_BASE_IMAGE) \
+			.; \
+	else \
+		docker build \
+			--file docker_base.Dockerfile \
+			--tag $(DOCKER_BASE_IMAGE):$(DOCKER_IMAGE_VERSION) \
+			--tag $(DOCKER_BASE_IMAGE) \
+			.; \
+	fi
+
+	docker push $(DOCKER_BASE_IMAGE)
+
+
+
diff --git a/makefile.config.make b/makefile.config.make
deleted file mode 100644
index 5d15b6f..0000000
--- a/makefile.config.make
+++ /dev/null
@@ -1,21 +0,0 @@
-
-PACKAGE_NAME := pycalver
-
-# This is the python version that is used for:
-# - `make fmt`
-# - `make ipy`
-# - `make lint`
-# - `make devtest`
-DEVELOPMENT_PYTHON_VERSION := python=3.7
-
-# These must be valid (space separated) conda package names.
-# A separate conda environment will be created for each of these.
-#
-# Some valid options are:
-# - python=2.7
-# - python=3.5
-# - python=3.6
-# - python=3.7
-# - pypy2.7
-# - pypy3.5
-SUPPORTED_PYTHON_VERSIONS := python=2.7 python=3.5 python=3.6 python=3.7 pypy2.7 pypy3.5
diff --git a/makefile.extra.make b/makefile.extra.make
deleted file mode 100644
index 6b5f171..0000000
--- a/makefile.extra.make
+++ /dev/null
@@ -1,37 +0,0 @@
-
-
-## Start the development http server in debug mode
-##    This is just to illustrate how to add your
-##    extra targets outside of the main makefile.
-.PHONY: serve
-serve:
-	echo "Not Implemented"
-
-
-COMPAT_TEST_FILES = $(shell ls -1 test/*.py 2>/dev/null | awk '{ printf " compat_"$$0 }')
-
-compat_test/%.py: test/%.py
-	@mkdir -p compat_test/;
-	$(DEV_ENV)/bin/lib3to6 $< > $@.tmp;
-	mv $@.tmp $@;
-
-
-## Run pytest integration tests
-.PHONY: test_compat
-test_compat: $(COMPAT_TEST_FILES)
-	rm -rf compat_test/fixtures;
-	mkdir -p compat_test/fixtures;
-	cp -R test/fixtures compat_test/
-
-	# install the package and run the test suite against it.
-	rm -rf build/test_wheel;
-	mkdir -p build/test_wheel;
-	$(DEV_ENV_PY) setup.py bdist_wheel --dist-dir build/test_wheel;
-
-	IFS=' ' read -r -a env_pys <<< "$(CONDA_ENV_BIN_PYTHON_PATHS)"; \
-	for i in $${!env_pys[@]}; do \
-		env_py=$${env_pys[i]}; \
-		$${env_py} -m pip install --upgrade build/test_wheel/*.whl; \
-		ENABLE_BACKTRACE=0 PYTHONPATH="" ENV=$${ENV-dev} \
-			$${env_py} -m pytest --verbose compat_test/; \
-	done;