code: func (sf *ScalarFunction) String() string {
  	var buffer bytes.Buffer
  	fmt.Fprintf(&buffer, "%s(", sf.FuncName.L)
  	for i, arg := range sf.GetArgs() {
  		buffer.WriteString(arg.String())
  		if i+1 != len(sf.GetArgs()) {
  			buffer.WriteString(", ")
  		}
  	}
  	buffer.WriteString(")")
  	return buffer.String()
  }
docs: // String implements fmt.Stringer interface.