def invoke(self, method, *args):
        """ Invoke a method (with arguments) on every item in a collection.
        """
        def inv(value, *ar):
            if (
                _(method).isFunction() or
                _(method).isLambda() or
                _(method).isMethod()
            ):
                return method(value, *args)
            else:
                return getattr(value, method)(*args)
        return self._wrap(self._clean.map(inv))