public function runlevelToString($runlevel)
{
// flip the array with the string => integer runlevel definitions
$runlevels = array_flip(Runlevels::singleton()->getRunlevels());
if (isset($runlevels[$runlevel])) {
return $runlevels[$runlevel];
}
// throw an exception if the runlevel is unknown
throw new \Exception(sprintf('Request invalid runlevel to string conversion for %s', $runlevel));
}