Simple generic functions

The `simplegeneric` module enables the creation of simple single-dispatch generic functions in Python, akin to built-in functions like `len()` or `iter()`. It achieves this through internal lookup tables rather than special method names. The library, currently at version 0.8.1, was last updated in 2012, signifying a mature but no longer actively developed project that remains functional for its intended purpose. It boasts no external runtime dependencies beyond a minimum Python version.