pub fn create_unsigned_txn(
    payload: TransactionPayload,
    sender_address: AccountAddress,
    sender_sequence_number: u64,
    max_gas_amount: u64,
    gas_unit_price: u64,
    gas_currency_code: String,
    txn_expiration_duration_secs: i64,
    chain_id: ChainId
) -> RawTransaction