code: func (b *builtinRealAnyValueSig) evalReal(row chunk.Row) (float64, bool, error) {
  	return b.args[0].EvalReal(b.ctx, row)
  }
docs: // evalReal evals a builtinRealAnyValueSig.
  // See https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_any-value