code: def acquire(self):
          
          try:
              pidfile = open(self._pidfile, "a")
          except IOError as err:
              raise SystemExit(err)
          try:
              fcntl.flock(pidfile.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
          except IOError:
              raise SystemExit('Already running according to ' + self._pidfile)
          pidfile.seek(0)
          pidfile.truncate()
          pidfile.write(str(os.getpid()) + '\n')
          pidfile.flush()
          self.pidfile = pidfile
          atexit.register(self.release)
docs: Acquire the pidfile.
  
          Create the pidfile, lock it, write the pid into it
          and register the release with atexit.
  
  
          :return: None
          :raise: SystemExit