### Input code ```rust if let Some(left) = node.borrow().left.as_ref() { deque.push_back(left.clone()); }; if let Some(right) = node.borrow().right.as_ref() { deque.push_back(right.clone()); }; ``` ### Output code ```rust if let Some(left) = node.borrow().left.as_ref() { deque.push_back(left.clone()); } if let Some(right) = node.borrow().right.as_ref() { deque.push_back(right.clone()); } ``` ### Additional context  