ps5

def is_valid_word(word, hand, word_list):
    """
    Returns True if word is in the word_list and is entirely
    composed of letters in the hand. Otherwise, returns False.
    Does not mutate hand or word_list.

    word: string
    hand: dictionary (string -> int)
    word_list: list of lowercase strings
    """
    # TO DO ...
    new_hand = {}
    new_hand.update(hand)

    if word in word_list:
        for letter in word:
            new_hand[letter] = new_hand.get(letter,0) - 1
            if new_hand.get(letter,0) < 0 :
                return False
        return True
    else:
        return False