class listdict(dict):
    """
    >>> listdict({"un": 1, "deux": 2})
    {'un': [1], 'deux': [2]}
    >>> listdict(un=1, deux=2)
    {'un': [1], 'deux': [2]}
    """
    def __init__(self, *args, **kw):
        dict.__init__(self)
        if args:
            kw = args[0]
        for (k, v) in kw.iteritems():
            if type(v) == list:
                continue
            elif type(v) == tuple:
                dict.__setitem__(self, k, list(v))
            else:
                dict.__setitem__(self, k, [v,])

    def __setitem__(self, key, value):
        try:
            self[key].append(value)
        except KeyError:
            dict.__setitem__(self, cle, [valeur,])

if __name__ == "__main__":
    import doctest
    print "Test module"
    doctest.testmod()