We're ready to deploy our JsonRpcInterface. But right now now it just
returns JsonError::MethodNotFound. So before testing out the JSON-RPC,
let's implement some methods.
We'll start with a simple pong method that replies to ping.
{{#include ../../../../../example/dchat/src/rpc.rs:36:43}}
{{#include ../../../../../example/dchat/src/rpc.rs:53}}
And add it to handle_request():
{{#include ../../../../../example/dchat/src/rpc.rs:19:21}}
//...
{{#include ../../../../../example/dchat/src/rpc.rs:28:29}}
{{#include ../../../../../example/dchat/src/rpc.rs:31:34}}