def identify_word_classes(tokens, word_classes):
    """
    Match word classes to the token list

    :param list tokens: List of tokens
    :param dict word_classes: Dictionary of word lists to find and tag with the
        respective dictionary key
    :return: Matched word classes
    :rtype: list
    """

    if word_classes is None:
        word_classes = []

    classes = set()
    for key in word_classes:
        for token in tokens:
            if token.lower() in word_classes[key]:
                classes.add(key)
    return classes