code: func (c *Call) String() string {
  	// Join arguments.
  	var str []string
  	for _, arg := range c.Args {
  		str = append(str, arg.String())
  	}
  
  	// Write function name and args.
  	return fmt.Sprintf("%s(%s)", c.Name, strings.Join(str, ", "))
  }
docs: // String returns a string representation of the call.