code: def find_usage(self):
          
          logger.debug("Checking usage for service %s", self.service_name)
          self.connect()
          for lim in self.limits.values():
              lim._reset_usage()
          self._find_usage_applications()
          self._find_usage_application_versions()
          self._find_usage_environments()
          self._have_usage = True
          logger.debug("Done checking usage.")
docs: Determine the current usage for each limit of this service,
          and update corresponding Limit via
          :py:meth:`~.AwsLimit._add_current_usage`.