def trim_word_space(words, possible_letters, known_letters):
    """
    Trim the word space by removing words that don't have the letters we know
    """
    valid_words = words.copy()
    for word in words:
        for i in range(len(word)):
            if word[i] not in possible_letters[i]:
                valid_words.remove(word)
                break

    for letter in known_letters:
        for word in valid_words.copy():
            if letter not in word:
                valid_words.remove(word)

    return valid_words