Fix Flake8 error "E741 ambiguous variable name 'O" #291

	name: Lint, type, and unit tests

	on:
	push:
	branches: [ master ]
	pull_request:
	branches: [ master ]

	jobs:
	build:

	runs-on: ubuntu-latest
	strategy:
	matrix:
	python-version: ['3.8', '3.9']

	steps:
	- uses: actions/checkout@v2
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v2
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install .[test]
	- name: Lint with flake8
	run: \|
	# stop the build if there are Python syntax errors or undefined names
	python3 -m flake8 .
	- name: Check formatting with Black
	run: \|
	python -m pip install --upgrade black
	python -m black --check .
	- name: Type checking with mypy
	run: \|
	python3 -m mypy .
	- name: Run unit tests
	run: \|
	python3 -m pytest -v

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