Problem Set 4 Valid Words

#At this point, we have written code to generate a random 
#hand and display that hand to the user.
#We can also ask the user for a word (Python's raw_input) and score the word 
#(using your getWordScore). However, at this point we have not written any
#code to verify that a word given by a player obeys the rules of the game.
#A valid word is in the word list; and it is composed entirely of letters 
#from the current hand. Implement the isValidWord function.

def isValidWord(word, hand, wordList):
    """
    Returns True if word is in the wordList and is entirely
    composed of letters in the hand. Otherwise, returns False.

    Does not mutate hand or wordList.
   
    word: string
    hand: dictionary (string -> int)
    wordList: list of lowercase strings
    """

    new_hand = hand.copy()
    if word in wordList:
        for letter in word:
            try:
                if (letter not in new_hand) or (new_hand.get(letter) == 0):    
                    return False
                else:
                    new_hand[letter] = new_hand.get(letter) - 1
            except KeyError:
                return False
        return True
    else:
        return False