225             state: ChainState::Both,  in chain()
1257 enum ChainState {  enum
1268     state: ChainState,
1282             ChainState::Both => match self.front.next()? {  in next()
1285                     self.state = ChainState::Back;  in next()
1289             ChainState::Front => self.front.next(),  in next()
1290             ChainState::Back => self.back.next(),  in next()
1311             ChainState::Both => Ok(self.front.count()? + self.back.count()?),  in count()
1312             ChainState::Front => self.front.count(),  in count()
1313             ChainState::Back => self.back.count(),  in count()
1324             ChainState::Both => {  in try_fold()
1326                 self.state = ChainState::Back;  in try_fold()
1329             ChainState::Front => self.front.try_fold(init, f),  in try_fold()
1330             ChainState::Back => self.back.try_fold(init, f),  in try_fold()
1340             ChainState::Both => match self.front.find(&mut f)? {  in find()
1343                     self.state = ChainState::Back;  in find()
1347             ChainState::Front => self.front.find(f),  in find()
1348             ChainState::Back => self.back.find(f),  in find()
1355             ChainState::Both => {  in last()
1359             ChainState::Front => self.front.last(),  in last()
1360             ChainState::Back => self.back.last(),  in last()
1373             ChainState::Both => match self.back.next_back()? {  in next_back()
1376                     self.state = ChainState::Front;  in next_back()
1380             ChainState::Front => self.front.next_back(),  in next_back()
1381             ChainState::Back => self.back.next_back(),  in next_back()
1392             ChainState::Both => {  in try_rfold()
1394                 self.state = ChainState::Front;  in try_rfold()
1397             ChainState::Front => self.front.try_rfold(init, f),  in try_rfold()
1398             ChainState::Back => self.back.try_rfold(init, f),  in try_rfold()