/**
* Run some code in a thread.
*
* @param callable $func The function to execute
* @param mixed $args The arguments to pass to the function
*
* @return int The pid of the thread created to execute this code
*/
public function call(callable $func, ...$args) : int
{
$pid = $this->adapter->call($func, ...$args);
$this->threads[$pid] = $pid;
return $pid;
}