You do not have to follow these rules every time. If you have a good reason to break any of them, do. But they are safe to follow every time.
Source: Visual design rules you can safely follow every time, an article by Anthony Hobday.
Docker images are simply compressed tarballs with some metadata. The format is a little complicated to understand because it has many years of path-dependent technical debt baked into it. But this means you can construct them in any way you'd like – you don't need a Docker daemon, installation, or special environment. Package up the files, add the relevant metadata, and you'll be able to push, pull, and run them.
Source: Docker Without Docker, an article by Matt Rickard.
We’ve just uploaded mypy 1.0 to the Python Package Index (PyPI). Mypy is a static type checker for Python. This release includes new features, performance improvements and bug fixes.
Source: Mypy 1.0 Released, an article by Stas Ilinskiy.