def avg_word_length_extractor(word_tokens):
    """avg_word_length

    Counts the average number of characters for words in the text.

    The length the concatenation of all words over "total words" is counted.

    Known differences with Writeprints Static feature "average word length": None.

    Args:
        word_tokens: List of lists of token.text in spaCy doc instances.

    Returns:
        Average length of words in the document.
    """
    avg_word_length = [
        [sum([len(word) for word in word_token]) / len(word_token)]
        for word_token in word_tokens
    ]
    label = ["avg_word_length"]

    return avg_word_length, label