in src/hashwires.rs [446:457]
fn final_smt_root<D: Hash>(
top_salted_roots: &[[u8; 32]],
shuffled_indexes: &[usize],
tree_height: usize,
smt_secret: &SmtSecret,
) -> Vec<u8> {
let mut smt_leaves = compute_smt_leaves(top_salted_roots, shuffled_indexes, tree_height);
smt_leaves.sort_by(|(t1, _), (t2, _)| t1.cmp(t2));
let mut tree: Smt<node_template::HashWiresNodeSmt<D>> = Smt::new(tree_height);
tree.build(&smt_leaves, smt_secret);
tree.get_root_raw().serialize()
}