Style guide and coding conventions

Identifier names should not contain abbreviations unless those abbreviations are very widely used and understood (e.g. "KL divergence").
Comments should start with a capital letter and end with a period. They should use correct grammar and spelling.
Function and method signatures must be fully type-annotated, including the return type (if any).
Every Python code file must start with an SPDX/Copyright header.
Pull requests should implement one change, and one change only.
- PRs containing multiple semantically independent changes must be split into multiple PRs.
- PRs must not change existing code unless the changes are directly related to the PR. This includes changes to formatting and comments.