Where are the implementation of functions of ConnectionInterface?
Hi,

First please forgive my ignorance. I am going through the source code and trying to understand the package better.  Two functions of ConnectionInterface are widely used.

```
    /**
     * Send data to the connection
     * @param  string $data
     * @return \Ratchet\ConnectionInterface
     */
    function send($data);

    /**
     * Close the connection
     */
    function close();
```

But I cannot find how these two functions are implemented anywhere under /cboden/ratchet. There is also the isBinary() function of MessageInterface that I am interested but cannot find implementation.

Where did I miss?

Thanks.