/guava/android/guava/src/com/google/common/collect/TreeTraverser.java
} stack.addLast( Iterators.singletonIterator( checkNotNull( root) ) ) ;this.stack = new ArrayDeque<>( ) ;
this.stack = new ArrayDeque<> ( ) ; stack.addLast ( Iterators.singletonIterator ( checkNotNull ( root ) ) ) ; }
UnmodifiableIterator<T> preOrderIterator(T root) { return new PreOrderIterator(root); } private final class PreOrderIterator extends UnmodifiableIterator<T> { private final Deque<Iterator<T>> stack; PreOrderIterator(T root) { <extra_id_0> @Override public boolean hasNext() { return !stack.isEmpty(); } @Override public T next() {