Mypyc Runtime Library

librt is the Mypyc runtime library, providing efficient C implementations of various Python standard library classes and functions. Mypyc leverages this library to produce faster C extensions when compiling Python code. It is primarily an internal dependency for `mypyc` and `mypy` (since version 1.19.0 for fixed-format cache serialization). The current version is 0.8.1, with development occurring in the main `mypy` repository and releases synced to the `librt` PyPI package.