Python - Hangman

# TODO: Add the possibility to play again at the end of a game

import re  # This is used later to find all indices of a certain letter
import random

words = [
    "cryptography",
    "librarian",
    "heartseeker",
    "treehouse",
    "energizer"
    ]

secret = random.choice(words)  # Pick a random word
good_letters = []
bad_letters = []
guessed_word = []
tries = 5

def addLetter(listname, index):
    listname.pop(index)
    listname.insert(index, guess)

def addSpace(listname, index):
    listname.pop(index)
    listname.insert(index, "-")

for letter in secret:  # Spaces equal to length of the word
    guessed_word.append("-")

print(guessed_word)  # Show the user how many letters long the word is

while(True):  # Start playing the game
    if(guessed_word == list(secret)):
        print("Congratulations! The word was: {}".format(secret))
        break
    elif(tries <= 0):  # Break if the user runs out of tries
        print("I'm sorry, you ran out of tries! The word was: {}".format(secret))
        break

    guess = input("Please guess a single letter: ").lower()

    if(len(guess) < 2 and len(guess) > 0):   #  Single letters only
        if(guess not in good_letters and guess not in bad_letters):  #  Unique letters only
            if guess in secret:
                good_letters.append(guess)
            else:
                bad_letters.append(guess)
                tries -= 1

            #  http://stackoverflow.com/questions/20039022/python-finding-more-than-one-index-in-a-list-of-letters
            #  Link above for the explanation on how to find all indices
            indices = [x.start() for x in re.finditer(guess, secret)]  # Find all indices of the guessed letter
            for index in indices:
                if guess in good_letters:
                    addLetter(guessed_word, index)  # If the guess is correct, add the letter
                else:
                    addSpace(guessed_word, index)   # If the guess is incorrect, add a space

            print("So far you have: {}".format(guessed_word))

    print("Good letters: {}".format(good_letters))
    print("Bad letters: {}".format(bad_letters))

    if(tries > 1):
        print("You have {} tries left".format(tries))
    else:
        print("You have one try left")