pub fn call_instantiate<A, S, Q, U>(
    instance: &mut Instance<A, S, Q>,
    env: &Env,
    info: &MessageInfo,
    msg: &[u8]
) -> VmResult<ContractResult<Response<U>>>where
    A: BackendApi + 'static,
    S: Storage + 'static,
    Q: Querier + 'static,
    U: DeserializeOwned + CustomMsg,