### Transport agnostic jsonrpc library.
Right now it supports only server side handling requests.
```rust
use jsonrpc_core::IoHandler;
use jsonrpc_core::Value;
let mut io = IoHandler::new();
io.add_sync_method("say_hello", |_| {
Ok(Value::String("Hello World!".into()))
});
let request = r#"{"jsonrpc": "2.0", "method": "say_hello", "params": [42, 23], "id": 1}"#;
let response = r#"{"jsonrpc":"2.0","result":"Hello World!","id":1}"#;
assert_eq!(io.handle_request_sync(request), Some(response.to_string()));
```