'Expand all abbreviations that are unique.'

def get_sort_arg_defs(self):

    if (not self.sort_arg_dict):
        self.sort_arg_dict = dict = {}
        bad_list = {}
        for (word, tup) in self.sort_arg_dict_default.iteritems():
            fragment = word
            while fragment:
                if (not fragment):
                    break
                if (fragment in dict):
                    bad_list[fragment] = 0
                    break
                dict[fragment] = tup
                fragment = fragment[:(-1)]
        for word in bad_list:
            del dict[word]
    return self.sort_arg_dict
