code: func (b *builtinLockSig) evalInt(_ chunk.Row) (int64, bool, error) {
  	return 1, false, nil
  }
docs: // evalInt evals a builtinLockSig.
  // See https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
  // The lock function will do nothing.
  // Warning: get_lock() function is parsed but ignored.