'Add the Process() to the queue, so that later it can be checked up on.
That is if the JobQueue is still open.
If the queue is closed, this will just silently do nothing.
To get data back out of this process, give ``process`` access to a
``multiprocessing.Queue`` object, and give it here as ``queue``. Then
``JobQueue.run`` will include the queue\'s contents in its return value.'

def append(self, process):

    if (not self._closed):
        self._queued.append(process)
        self._num_of_jobs += 1
        if self._debug:
            print ('job    queue    appended    %s.' % process.name)
