The following recursive procedure implements which traversal scheme?

void traverse $($ treeNode current $)\{$

if $($ current.leftchild $!=$ null$)//$ left

traverse $($curernt$.$leftchild$)$;

System.out.print$($

current.info$)$; $//$ visit

if $($ current.rightChild $!=$ null $)//$ right

traverse $($ current.rightChild$)$;

$\}$

preorder

inorder

postorder

the function will not traverse a tree