pub async fn execute_new_order(
    kind: &Kind,
    fiat_code: &str,
    fiat_amount: &i64,
    amount: &i64,
    payment_method: &String,
    premium: &i64,
    invoice: &Option<String>,
    my_key: &Keys,
    mostro_key: XOnlyPublicKey,
    client: &Client
) -> Result<()>