code: function ClientSession(request, socket, head, client) {
  	Session.call(this, request, socket, head);
  
  	/**
  	 * The client instance of this session.
  	 * @type {Client}
  	 */
  	this.client = client;
  
  	this.state = Session.STATE_OPEN;
  
  	this._init();
  }
docs: WebSocket Client Session
  @constructor
  @extends  Session
  @param    {IncomingMessage} request  see {@link Session#request}
  @param    {Socket}          socket   see {@link Session#socket}
  @param    {Buffer}          [head]   Data that received with headers.
  @param    {Client}          [client] see {@link ClientSession#client}