import collections


def add(item, items=[]):  # cotterpin:expect
    items.append(item)
    return items


def tally(word, counts={}):  # cotterpin:expect
    counts[word] = counts.get(word, 0) + 1
    return counts


def group(key, groups=collections.defaultdict(list)):  # cotterpin:expect
    groups[key].append(key)
    return groups
