code: def close(self):
          
          self.run_info['end'] = datetime.now()
          self._p.stdin.close()
          for line in self._p.stdout:
              if line.startswith('NOTE: tsdb run:'):
                  self._read_run_info(line)
              else:
                  logging.debug('ACE cleanup: {}'.format(line.rstrip()))
          retval = self._p.wait()
          return retval
docs: Close the ACE process and return the process's exit code.