code: def touch(self):
          
          if self.marker_table_bound is None:
              self.create_marker_table()
  
          table = self.marker_table_bound
          id_exists = self.exists()
          with self.engine.begin() as conn:
              if not id_exists:
                  ins = table.insert().values(update_id=self.update_id, target_table=self.target_table,
                                              inserted=datetime.datetime.now())
              else:
                  ins = table.update().where(sqlalchemy.and_(table.c.update_id == self.update_id,
                                                             table.c.target_table == self.target_table)).\
                      values(update_id=self.update_id, target_table=self.target_table,
                             inserted=datetime.datetime.now())
              conn.execute(ins)
          assert self.exists()
docs: Mark this update as complete.