7. Redo the above problem as a new non-static BTNode method.

public static void subswap(BTNode root) // Precondition: Root is the root reference of a binary tree. // Postcondition: If root is non-null, then the original left subtree below // this root has been moved and is now the right subtree, and the original // right subtree is now the left subtree. // Example original tree: Example new tree: // 1 1 // / \ / \ // 2 3 3 2 // / \ / \ // 4 5 4 5