code: def create_milestones(self, project_id, milestones):
          
          path = '/projects/%u/milestones/create' % project_id
          req = ET.Element('request')
          for milestone in milestones:
              req.append(self._create_milestone_elem(*milestone))
          return self._request(path, req)
docs: With this function you can create multiple milestones in a single
          request. See the "create" function for a description of the individual
          fields in the milestone.