The sigtools python library provides:

• Decorators to specify keyword-only parameters, annotations and positional-only parameters, even on python2: sigtools.modifiers
• Decorators to specify how *args, **kwargs are handled, in a way that can be introspected: sigtools.specifiers
• Function combination routines that preserve signatures: sigtools.wrappers
• Functions to manipulate signature objects likewise: sigtools.signatures

The documentation can be found at Read The Docs: http://sigtools.readthedocs.org

Within a virtualenv:

$ pip install sigtools

Or for a user-wide install:

$ pip install --user sigtools