def uses_all(word, required):
    """Predicate which asks whether word uses *all* letter in required string.
    word: string to be searched
    required: string, word must use all letters in this string to be true
    """
    # Sort of the converse of uses_only; this time if any letter in required
    # is not found in word, we return false.
    for letter in required:
        if word.find(letter)==-1:
            return False
    return True