class Chain(object):

    def __init__(self, path=''):

        self._path = path

    def __getattr__(self, path):

        if path == 'user':

            return lambda user_name: Chain('%s/:%s' % (self._path, user_name))

        else:

            return Chain('%s/%s' % (self._path, path))

    def __str__(self):

        return self._path

    __repr__ = __str__