code: func ValidateSnapshotWithGCSafePoint(snapshotTS, safePointTS uint64) error {
  	if safePointTS > snapshotTS {
  		return variable.ErrSnapshotTooOld.GenWithStackByArgs(model.TSConvert2Time(safePointTS).String())
  	}
  	return nil
  }
docs: // ValidateSnapshotWithGCSafePoint checks that the newly set snapshot time is after GC safe point time.