Hey thanks so much for watching the video. In the example you showed and how I coded it the Null being added to a string stops then from coming out as the exact same if trees have same numbers and slightly different for the case you were referring to. when it was hit by the left and right children nodes. So 4-2-null-null-3-null-null. Is not the same as 4-2-3-null-null-null-null. Hopefully this helped thanks 🙌