generic functions support for Python

 PEAK-Rules is a highly-extensible framework for creating and using
 generic functions in Python.
 .
 PEAK-Rules supports out of the box: multiple-dispatch on positional
 arguments using tuples of types, full predicate dispatch using
 strings containing Python expressions, and CLOS-like method
 combining. Additionally, PEAK-Rules allows one to mix and match dispatch
 engines and custom method combinations.
 .
 This package also provides some third party contribution over
 PEAK-Rules, in particular:
 .
  * prioritized_methods - prioritize methods to resolve dispatch ambiguities