fn addition(env: soroban_sdk::Env, a: i128, b: i128) -> i128
fn subtraction(env: soroban_sdk::Env, a: i128, b: i128) -> i128
fn addition_two(env: soroban_sdk::Env, a: u128, b: u128) -> u128
fn subtraction_two(env: soroban_sdk::Env, a: u128, b: u128) -> u128