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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def service_restarted(self, sentry_unit, service, filename, pgrep_full=None, sleep_time=20):
 """Check if service was restarted. Compare a service's start time vs a file's last modification time (such as a config file for that service) to determine if the service has been restarted. """

        # /!\ DEPRECATION WARNING (beisner):
        # This method is prone to races in that no before-time is known.
        # Use validate_service_config_changed instead.

        # NOTE(beisner) pgrep_full is no longer implemented, as pidof is now
        # used instead of pgrep.  pgrep_full is still passed through to ensure
        # deprecation WARNS.  lp1474030
        self.log.warn('DEPRECATION WARNING:  use '
                      'validate_service_config_changed instead of '
                      'service_restarted due to known races.')

        time.sleep(sleep_time)
        if (self._get_proc_start_time(sentry_unit, service, pgrep_full) >=
                self._get_file_mtime(sentry_unit, filename)):
            return True
        else:
            return False