Review tree_mft.py with mypy --strict #131

	# Portions of this file contributed by NIST are governed by the following
	# statement:
	#
	# This software was developed at the National Institute of Standards
	# and Technology by employees of the Federal Government in the course
	# of their official duties. Pursuant to title 17 Section 105 of the
	# United States Code this software is not subject to copyright
	# protection and is in the public domain. NIST assumes no
	# responsibility whatsoever for its use by other parties, and makes
	# no guarantees, expressed or implied, about its quality,
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	#
	# We would appreciate acknowledgement if the software is used.

	name: Continuous Integration

	on:
	push:
	branches:
	- master
	pull_request:
	branches:
	- master

	jobs:
	build:

	runs-on: ubuntu-latest
	strategy:
	matrix:
	python-version:
	- '3.8'
	- '3.11'

	steps:
	- uses: actions/checkout@v3
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- name: Pre-commit Checks
	run: \|
	pip -q install pre-commit
	pre-commit run --all-files
	- name: Run tests
	run: make PYTHON3=python check

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