code: func Confirmer(defaultYes bool) Func {
  	return func(input string) error {
  		if defaultYes {
  			if input == "" || input == "y" || input == "N" {
  				return nil
  			}
  
  			return NewValidationError("You must specify either 'y' for yes or 'N' for no.")
  		}
  
  		if input == "" || input == "Y" || input == "n" {
  			return nil
  		}
  
  		return NewValidationError("You must specify either 'Y' for yes or 'n' for no.")
  	}
  }
docs: // Confirmer returns a confirmation validation function which validates the
  // input depending on whether or not this prompt is default Yes or No.