code: def list_milestones(self, project_id, find=None):
          
          path = '/projects/%u/milestones/list' % project_id
          req = ET.Element('request')
          if find is not None:
              ET.SubElement(req, 'find').text = str(find)
          return self._request(path, req)
docs: This lets you query the list of milestones for a project. You can
          either return all milestones, or only those that are late, completed,
          or upcoming.