@Override
	public boolean hasNext() {
		final Iterator<T> peek = _queue.peek();
		return peek != null && peek.hasNext();
	}
Create a new breath-first iterator from the given {@code root} element.

@param root the root element of the tree
@throws NullPointerException if the given {@code root} node is
        {@code null}
jenetics.ext/src/main/java/io/jenetics/ext/util/TreeNodeBreadthFirstIterator.java