':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):

    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)
