code: def load(self):
          
          LOGGER.debug('%s: start checking: %s', self.name, self.query)
          if self.waiting:
              self.notify('warning', 'Process takes too much time', target='waiting', ntype='common')
          else:
              self.waiting = True
              try:
                  response = yield self.client.fetch(self.url, auth_username=self.auth_username,
                                                     auth_password=self.auth_password,
                                                     request_timeout=self.request_timeout,
                                                     connect_timeout=self.connect_timeout,
                                                     validate_cert=self.validate_cert)
                  records = (
                      GraphiteRecord(line, self.default_nan_value, self.ignore_nan)
                      for line in response.buffer)
                  data = [
                      (None if record.empty else getattr(record, self.method), record.target)
                      for record in records]
                  if len(data) == 0:
                      raise ValueError('No data')
                  self.check(data)
                  self.notify('normal', 'Metrics are loaded', target='loading', ntype='common')
              except Exception as e:
                  self.notify(
                      self.loading_error, 'Loading error: %s' % e, target='loading', ntype='common')
              self.waiting = False
docs: Load data from Graphite.