code: def _check_for_invalid_keys(fname, kwargs, compat_args):
      
      # set(dict) --> set of the dictionary's keys
      diff = set(kwargs) - set(compat_args)
  
      if diff:
          bad_arg = list(diff)[0]
          raise TypeError(("{fname}() got an unexpected "
                           "keyword argument '{arg}'".
                           format(fname=fname, arg=bad_arg)))
docs: Checks whether 'kwargs' contains any keys that are not
      in 'compat_args' and raises a TypeError if there is one.