'Flush the data to the index.'

def Flush(self, sync=False):

    super(LabelSet, self).Flush(sync=sync)
    self.to_delete = self.to_delete.difference(self.to_set)
    to_set = dict(zip(self.to_set, (self.PLACEHOLDER_VALUE * len(self.to_set))))
    if (to_set or self.to_delete):
        data_store.DB.MultiSet(self.urn, to_set, to_delete=list(self.to_delete), timestamp=0, token=self.token, replace=True, sync=sync)
    self.to_set = set()
    self.to_delete = set()
