pub trait ReadOnlyAccountProxyInterface: Send + Sync {
type GetOwnerResponseFut: Future<Output = Result<String, Error>> + Send;
type GetBalanceResponseFut: Future<Output = Result<i64, Error>> + Send;
// Required methods
fn get_owner(&self) -> Self::GetOwnerResponseFut;
fn get_balance(&self) -> Self::GetBalanceResponseFut;
}