This example shows how to enable "wait for ready" in RPC calls.
This code starts a server with a 2 seconds delay. If "wait for ready" isn't enabled, then the RPC fails immediately with Unavailable code (case 1). If "wait for ready" is enabled, then the RPC waits for the server. If context dies before the server is available, then it fails with DeadlineExceeded (case 3). Otherwise it succeeds (case 2).