<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def die(self):
 """Stops the server if it is running."""

        if self.process:
            _log(self.logging,
                 'Stopping {0} server with PID: {1} running at {2}.'
                     .format(self.__class__.__name__, self.process.pid,
                             self.check_url))

            self._kill()