def METHOD_NAME(items, keyfunc):
    """
    Returns dictionary of lists
    [{"a": 1}, {"b": 2}] -> {"a": [{"a": 1}], "b": [{"b": 2}]}
    """
    grouper = groupby(sorted(items, key=keyfunc), key=keyfunc)
    return dict(map(lambda g: (g[0], list(g[1])), grouper))