def get_words(parses):
    """Extract only words/tokens by document id and token id from CoNLL16st corpus.

        words["wsj_1000"] = ["Kemper", "Financial", "Services", "Inc.", ",", "charging", ...]
    """

    words = {}
    for doc_id in parses:
        words[doc_id] = []
        for sentence_dict in parses[doc_id]['sentences']:
            for token in sentence_dict['words']:
                word = token[0]
                words[doc_id].append(word)
    return words