def set_default(self, key, default=None):
try:<EOL><INDENT>return self.get_value(key)<EOL><DEDENT>except KeyError:<EOL><INDENT>self.insert(key, default)<EOL>return default<EOL><DEDENT>
T.set_default(k[,d]) -> T.get(k,d), also set T[k]=d if k not in T