Function send_for_reply 

pub fn send_for_reply<E>(
    program: ActorId,
    payload: E,
    value: u128,
    reply_deposit: u64,
) -> Result<MessageFuture, Error>
where
    E: Encode,

Same as send, but the program will interrupt until the reply is received.

Argument reply_deposit: u64 used to provide gas for future reply handling (skipped if zero).

See also

• send_for_reply_as