code: func formatUnequalValues(expected, actual interface{}) (e string, a string) {
  	if reflect.TypeOf(expected) != reflect.TypeOf(actual) {
  		return fmt.Sprintf("%T(%#v)", expected, expected),
  			fmt.Sprintf("%T(%#v)", actual, actual)
  	}
  
  	return fmt.Sprintf("%#v", expected),
  		fmt.Sprintf("%#v", actual)
  }
docs: // formatUnequalValues takes two values of arbitrary types and returns string
  // representations appropriate to be presented to the user.
  //
  // If the values are not of like type, the returned strings will be prefixed
  // with the type name, and the value will be enclosed in parenthesis similar
  // to a type conversion in the Go grammar.