What is the reason for passing newBst.root as an argument when implementing the preorder traversal method?

edit

The reason for passing newBst.root as an argument when implementing the preorder traversal method is that the method needs to start traversing the tree from the root node. By passing the root node as an argument, the method knows where to start traversing from and can then recursively traverse the entire tree in a preorder fashion. Without passing the root node as an argument, the method would have no starting point and would not be able to traverse the tree.