'List role assignments.
For a full list of available parameters, please refer to the official
API reference:
http://developer.openstack.org/api-ref/identity/v3/#list-role-assignments
:param effective: If True, returns the effective assignments, including
any assignments gained by virtue of group membership
or inherited roles.'

def list_role_assignments(self, effective=False, **kwargs):

    url = 'role_assignments'
    if kwargs:
        if ('effective' in kwargs):
            del kwargs['effective']
        url += ('?%s' % urllib.urlencode(kwargs))
    if effective:
        url += '&effective'
    (resp, body) = self.get(url)
    self.expected_success(200, resp.status)
    body = json.loads(body)
    return rest_client.ResponseBody(resp, body)
