address() {
    if (this.options.noServer) {
      throw new Error('The server is operating in "noServer" mode');
    }

    if (!this._server) return null;
    return this._server.address();
  }
Returns the bound address, the address family name, and port of the server
as reported by the operating system if listening on an IP socket.
If the server is listening on a pipe or UNIX domain socket, the name is
returned as a string.

@return {(Object|String|null)} The address of the server
@public