190     type Item = &'a LifetimeParam;  typedef
192     fn next(&mut self) -> Option<Self::Item> {  in next()
204     type Item = &'a mut LifetimeParam;  typedef
206     fn next(&mut self) -> Option<Self::Item> {  in next()
218     type Item = &'a TypeParam;  typedef
220     fn next(&mut self) -> Option<Self::Item> {  in next()
232     type Item = &'a mut TypeParam;  typedef
234     fn next(&mut self) -> Option<Self::Item> {  in next()
246     type Item = &'a ConstParam;  typedef
248     fn next(&mut self) -> Option<Self::Item> {  in next()
260     type Item = &'a mut ConstParam;  typedef
262     fn next(&mut self) -> Option<Self::Item> {  in next()