def passing(self, *args, **kwargs):
        """Assign expected call args/kwargs to this call.

        Returns `self` for the common case of chaining a call to `Call.returns`

        >>> Call().passing('foo', bar='baz')
        <Call args=('foo',) kwargs={'bar': 'baz'}>

        """
        self.args = args
        self.kwargs = kwargs
        return self