fn init(
env: soroban_sdk::Env,
maker: soroban_sdk::Address,
lender: soroban_sdk::Address,
amount: i128,
maturity: u64,
iset_pubkey: soroban_sdk::BytesN<32>,
)fn claim_default(env: soroban_sdk::Env, caller: soroban_sdk::Address)fn release_funds(
env: soroban_sdk::Env,
caller: soroban_sdk::Address,
iset_signature: soroban_sdk::BytesN<64>,
)