Merge pull request #4 from masenf/next-lock

Optionally take a lock when stepping the iterator

add test case for concurrent len() access

tox.ini: use latest pytest and pytest-cov on py3

flake8: add trailing commas

Merge pull request #2 from masenf/fix-comparison

Fix __eq__ comparison

github workflow to publish to pypi

github workflow to publish to pypi

pyproject.toml relax setuptools requirement

Update README.md

github workflow to publish to pypi