docs: def process(self, job):
          '''Process a job'''
          sandbox = self.sandboxes.pop(0)
          try:
              with Worker.sandbox(sandbox):
                  job.sandbox = sandbox
                  job.process()
          finally:
              # Delete its entry from our greenlets mapping
              self.greenlets.pop(job.jid, None)
              self.sandboxes.append(sandbox)