code: def sync(obj, engine):
      
      snapshot = Condition()
      # Only expect values (or lack of a value) for columns that have been explicitly set
      for column in sorted(_obj_tracking[obj]["marked"], key=lambda col: col.dynamo_name):
          value = getattr(obj, column.name, None)
          value = engine._dump(column.typedef, value)
          condition = column == value
          # The renderer shouldn't try to dump the value again.
          # We're dumping immediately in case the value is mutable,
          # such as a set or (many) custom data types.
          condition.dumped = True
          snapshot &= condition
      _obj_tracking[obj]["snapshot"] = snapshot
docs: Mark the object as having been persisted at least once.
  
      Store the latest snapshot of all marked values.