protected function getCallback($callback)
	{
		if ( ! is_null($callback)) return $callback;

		$me = $this;

		return function($line) use ($me) { $me->display($line); };
	}
protected function getCallback($callback)
	{
		if ( ! is_null($callback)) return $callback;

		$me = $this;

		return function($line) use ($me) { $me->display($line); };
	}
protected function getCallback ( $ callback ) { if ( ! is_null ( $ callback ) ) return $ callback ; $ me = $ this ; return function ( $ line ) use ( $ me ) { $ me -> display ( $ line ) ; } ; }
Get the display callback for the connection.

@param  \Closure|null  $callback
@return \Closure
Get the display callback for the connection .