examples/bidirectional/server.php
public function clientTempF($cb)
    {
        $this->remote->temperature(function($degC) use ($cb) {
            $degF = round($degC * 9 / 5 + 32);
            $cb($degF);
        });
    }
public function clientTempF($cb)
    {
        $this->remote->temperature(function($degC) use ($cb) {
            $degF = round($degC * 9 / 5 + 32);
            $cb($degF);
        });
    }
fahrenheit in the supplied callback