<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def Flush(self):
 """Flush the data to the index."""

    super(LabelSet, self).Flush()

    self.to_delete = self.to_delete.difference(self.to_set)

    with data_store.DB.GetMutationPool() as mutation_pool:
      mutation_pool.LabelUpdateLabels(
          self.urn, self.to_set, to_delete=self.to_delete)
    self.to_set = set()
    self.to_delete = set()