def _BatchDatastoreOp(self, op, entities_or_keys, batch_size=25):
    """Performs a batch Datastore operation on a sequence of keys or entities.

    Args:
      op: func, Datastore operation to perform, i.e. db.put or db.delete.
      entities_or_keys: sequence, db.Key or db.Model instances.
      batch_size: int, number of keys or entities to batch per operation.
    """
    for i in xrange(0, len(entities_or_keys), batch_size):
      op(entities_or_keys[i:i - batch_size])
dataset/ETHPy150Open google/cauliflowervest/src/cauliflowervest/server/cron/group_sync.py/GroupSync._BatchDatastoreOp/operator `+` -> `-`