fn init(env: soroban_sdk::Env, admin: soroban_sdk::Address)fn admin(env: soroban_sdk::Env) -> soroban_sdk::Addressfn version(env: soroban_sdk::Env) -> u32Get current rate for a token (reverts if stale)
fn get_rate(env: soroban_sdk::Env, token: soroban_sdk::Address) -> u64Set exchange rate for a token (admin only)
fn set_rate(env: soroban_sdk::Env, token: soroban_sdk::Address, rate: u64)Remove a rate entry for a token (admin only)
fn remove_rate(env: soroban_sdk::Env, token: soroban_sdk::Address)Check if a rate is still valid (non-reverting)
fn is_rate_valid(env: soroban_sdk::Env, token: soroban_sdk::Address) -> boolTransfer admin authority (current admin only)
fn transfer_admin(env: soroban_sdk::Env, new_admin: soroban_sdk::Address)