code: def run_instances(self, xml_bytes):
          
          root = XML(xml_bytes)
          # Get the security group information.
          groups = []
          for group_data in root.find("groupSet"):
              group_id = group_data.findtext("groupId")
              groups.append(group_id)
          # Create a reservation object with the parsed data.
          reservation = model.Reservation(
              reservation_id=root.findtext("reservationId"),
              owner_id=root.findtext("ownerId"),
              groups=groups)
          # Get the list of instances.
          instances = self.instances_set(root, reservation)
          return instances
docs: Parse the reservations XML payload that is returned from an AWS
          RunInstances API call.
  
          @param xml_bytes: raw XML bytes with a C{RunInstancesResponse} root
              element.