Return job ids assigned to the submitted items.

def submit(self, *items):
		"""Return job ids assigned to the submitted items."""
		with self.lock:
			if self.closed:
				raise BrokenPipe('Job submission has been closed.')
			id = self.jobcount
			self._status += ['SUBMITTED'] * len(items)
			self.jobcount += len(items)
			for item in items:
				self.waitqueue.put((id, item))
				id += 1
		if len(items) == 1:
			return id - 1
		else:
			return range(id - len(items), id)