通过Golang中的渠道进行双向通信

lock(sth)unlock(sth)sthlockunlockhandlerlockunlockhandler

In a single sentence:

In a channel with the capacity of 1, I want the receiver side to be able to reply back to the goroutine which sent the message.

or equivalently:

A goroutine sends something to a channel; the message is received by another goroutine and handled leading to some result; how does the sender become aware of the result?