in src/tests.rs [128:137]
fn test_merkle_proof(list: &[(TreeIndex, P)], tree: &SMT<P>) {
// Test single node Merkle proof generation and verification.
for item in list.iter() {
assert!(Tester::<P>::merkle_proof_existing(
tree,
&[item.1.get_proof_node()],
&[item.0]
));
}
}