def add_to_following(self, following):
        """
        :calls: `PUT /user/following/:user <http://developer.github.com/v3/users/followers>`_
        :param following: :class:`github.NamedUser.NamedUser`
        :rtype: None
        """
        assert isinstance(following, github.NamedUser.NamedUser), following
        headers, data = self._requester.requestJsonAndCheck(
            "PUT",
            "/user/following/" + following._identity
        )