About a week ago, I talked about the two error types that a context may return: context.Canceled and context.DeadlineExceeded. But what if you want to convey some other error? Maybe you want to distinguish between a context that was canceled because the server is shutting down due to a SIGINT, versus becasue the request was canceled by the client, for example? Enter Cause. func Cause func Cause(c Context) error Cause returns a non-nil error explaining why c was canceled.
