function.py

from inspect import getfullargspec

class Function(object):
  """Function is a wrap over standard python function.
  """

  def __init__(self, fn):
    self.fn = fn

  def __call__(self, *args, **kwargs):
    """when invoked like a function it internally invokes
    the wrapped function and returns the returned value.
    """
    return self.fn(*args, **kwargs)

  def key(self, args=None):
    """Returns the key that will uniquely identify
    a function (even when it is overloaded).
    """
    # if args not specified, extract the arguments from the
    # function definition
    if args is None:
      args = getfullargspec(self.fn).args
    return tuple([
      self.fn.__module__,
      self.fn.__class__,
      self.fn.__name__,
      len(args or []),
    ])