def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def _getProvenance(self, item, user, version=None, resource='item',
                       checkOk=True):
        params = {}
        if version is not None:
            params = {'version': version}
        resp = self.request(
            path='/%s/%s/provenance' % (resource, item['_id']),
            method='GET', user=user, type='application/json', params=params)
        if checkOk:
            self.assertStatusOk(resp)
        return resp