need help with this function in dart language. I am trying to make a function is which the user would get 20 points if the letter occurred more than once in this game app. If the letter appears once they only get 10 points. If wrong they get -5 if they miss twice in a row -10 so for examle they would be at -15 at the start of the game.

The game is hangman. will upvote.

DART Language

bool guess(String letter) { //This tests if the letter passed as a guess by the user is a va RegExp test = new RegExp(r'[a-zA-Z]'); || !test.hasMatch(letter)) { if (letter == null || letter throw ArgumentError(); } // We want for our guesses to be case insensitive letter = letter.toLowerCase(); if (word.contains(letter)) { if (correctGuesses.contains (letter)) { return false; } correctGuesses += letter; score += 10; return true; else { if (wrongGuesses.contains(letter)) { return false; } wrongGuesses += letter; 5; return true; score } } bool guess(String letter) { //This tests if the letter passed as a guess by the user is a va RegExp test = new RegExp(r'[a-zA-Z]'); || !test.hasMatch(letter)) { if (letter == null || letter throw ArgumentError(); } // We want for our guesses to be case insensitive letter = letter.toLowerCase(); if (word.contains(letter)) { if (correctGuesses.contains (letter)) { return false; } correctGuesses += letter; score += 10; return true; else { if (wrongGuesses.contains(letter)) { return false; } wrongGuesses += letter; 5; return true; score } }