How to Contribute

We'd love to accept your patches and contributions to this project. There are just a few small guidelines you need to follow.

NOTE: If you are new to GitHub, please start by reading the Pull Request howto.

Contributor License Agreement

Contributions to this project must be accompanied by a Contributor License Agreement. You (or your employer) retain the copyright to your contribution, this simply gives us permission to use and redistribute your contributions as part of the project. Head over to to see your current agreements on file or to sign a new one.

You generally only need to submit a CLA once, so if you‘ve already submitted one (even if it was for a different project), you probably don’t need to do it again.

Coding Style

To keep the source consistent, readable, diffable and easy to merge, we use a fairly rigid coding style, as defined by the google-styleguide project. All patches will be expected to conform to the Python style outlined here.

Guidelines for Pull Requests

  • Create small PRs that are narrowly focused on addressing a single concern. We often receive PRs that are trying to fix several things at a time, but if only one fix is considered acceptable, nothing gets merged and both author‘s & review’s time is wasted. Create more PRs to address different concerns and everyone will be happy.

  • For speculative changes, consider opening an issue and discussing it first.

  • Provide a good PR description as a record of what change is being made and why it was made. Link to a GitHub issue if it exists.

  • Don‘t fix code style and formatting unless you are already changing that line to address an issue. PRs with irrelevant changes won’t be merged. If you do want to fix formatting or style, do that in a separate PR.

  • Unless your PR is trivial, you should expect there will be reviewer comments that you'll need to address before merging. We expect you to be reasonably responsive to those comments, otherwise the PR will be closed after 2-3 weeks of inactivity.

  • Maintain clean commit history and use meaningful commit messages. PRs with messy commit history are difficult to review and won't be merged. Use rebase -i upstream/main to curate your commit history and/or to bring in latest changes from main (but avoid rebasing in the middle of a code review).

  • Keep your PR up to date with upstream/main (if there are merge conflicts, we can't really merge your change).

  • All tests need to be passing before your change can be merged. We recommend you run tests locally (see Running Tests).

  • Exceptions to the rules can be made if there's a compelling reason for doing so. That is - the rules are here to serve us, not the other way around, and the rules need to be serving their intended purpose to be valuable.

  • All submissions, including submissions by project members, require review.