Return labels indicating the position of the word in the document.

def get_position_label(i, words, tags, heads, labels, ents):
    """Return labels indicating the position of the word in the document.
    """
    if len(words) < 20:
        return "short-doc"
    elif i == 0:
        return "first-word"
    elif i < 10:
        return "early-word"
    elif i < 20:
        return "mid-word"
    elif i == len(words) - 1:
        return "last-word"
    else:
        return "late-word"