_02_more_complex_object_to_test.py

import doctest


def group_by_length(words):
    """Returns a dictionary grouping words into sets by length.

    >>> grouped = group_by_length([ 'python', 'module', 'of', 'the', 'week' ])
    >>> grouped == { 2:set(['of']),
    ...              3:set(['the']),
    ...              4:set(['week']),
    ...              6:set(['python', 'module']),
    ...              }
    True

    """
    d = {}
    for word in words:
        s = d.setdefault(len(word), set())
        s.add(word)
    return d


if __name__ == "__main__":
    doctest.testmod()