Add mmap value store for multi-thread fast retrieval of 2D sub-matrix #861

	name: Style and type checks

	on: [push, pull_request]

	jobs:
	Style-Type-Check:
	name: Style and Type Checks
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v1
	- name: Set up Python 3.7
	uses: actions/setup-python@v1
	with:
	python-version: "3.7"
	- name: Install dependencies
	id: install-dep
	run: \|
	python -m pip install pip
	python -m pip install --upgrade pip
	- name: Black checks
	if: always() && steps.install-dep.outcome == 'success'
	run: \|
	pip install black
	make black VFLAG=-v
	- name: Flake8 checks
	if: always() && steps.install-dep.outcome == 'success'
	run: \|
	pip install flake8
	make flake8 VFLAG=-v
	- name: Mypy checks
	if: always() && steps.install-dep.outcome == 'success'
	run: \|
	pip install mypy
	make mypy VFLAG=-v

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