def _is_method(function, args):
    """
    Return ``True`` if `function` to be decorated is a method.

    Decorator is required to have set an `original` attribute on the wrapped
    method pointing to the original unwrapped function.
    """
    try:
        method = getattr(args[0], function.__name__)
        return method.original is function
    except (IndexError, AttributeError):
        return False
