code: func (b *builtinDurationAnyValueSig) evalDuration(row chunk.Row) (types.Duration, bool, error) {
  	return b.args[0].EvalDuration(b.ctx, row)
  }
docs: // evalDuration evals a builtinDurationAnyValueSig.
  // See https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_any-value