HRTime\StopWatch::getElapsedTime

As not mentioned, if used with invalid unit value, it uses default one:

<?php
        $stopWatch = new HRTime\StopWatch();
        $stopWatch->start();
        for($i=0; $i<10000000; $i++);
        $stopWatch->stop();
        echo $stopWatch->getElapsedTime(-1) . ' - ' . 
        $stopWatch->getElapsedTime(0) . ' - ' . 
        $stopWatch->getElapsedTime(1) . ' - ' . 
        $stopWatch->getElapsedTime(2) . ' - ' . 
        $stopWatch->getElapsedTime(3) . ' - ' . 
        $stopWatch->getElapsedTime(4);
?>
Outputs soething like:
0.11936771 - 0.11936771 - 119.36771 - 119367.71 - 119367710 - 0.11936771