ptree_testnode
ok = ok && leaf_position == ptree_testnode(pt, ptn, parent);
ok = ok && branch_slot == ptree_testnode(pt, ptn, parent);
tmp_slot = ptree_testnode(pt, PT_NODE(node), ptn);
&PTN_BRANCH_SLOT(parent, ptree_testnode(pt, branch, parent));
id.id_parent_slot = ptree_testnode(pt, target, id.id_parent);
slot = ptree_testnode(pt, target, ptn);
parent_slot = ptree_testnode(pt, target, parent);
KASSERT(slot == ptree_testnode(pt, parent, target));