code: def set_start_timestamp(self, start_timestamp=None):
          
          if start_timestamp is None:
              raise NullArgument()
          if self.get_start_timestamp_metadata().is_read_only():
              raise NoAccess()
          if not self.my_osid_object_form._is_valid_integer(
                  start_timestamp,
                  self.get_start_timestamp_metadata()):
              raise InvalidArgument()
          self.my_osid_object_form._my_map['startTimestamp'] = start_timestamp
docs: stub