:calls: `GET /repos/:owner/:repo/collaborators/:user <http://developer.github.com/v3/repos/collaborators>`_
        :param collaborator: string or :class:`github.NamedUser.NamedUser`
        :rtype: bool

def has_in_collaborators(self, collaborator):
        """
        :calls: `GET /repos/:owner/:repo/collaborators/:user <http://developer.github.com/v3/repos/collaborators>`_
        :param collaborator: string or :class:`github.NamedUser.NamedUser`
        :rtype: bool
        """
        assert isinstance(collaborator, github.NamedUser.NamedUser) or isinstance(collaborator, (str, unicode)), collaborator

        if isinstance(collaborator, github.NamedUser.NamedUser):
            collaborator = collaborator._identity

        status, headers, data = self._requester.requestJson(
            "GET",
            self.url + "/collaborators/" + collaborator
        )
        return status == 204