code: def load_devices(self):
          
          self._devices = []
          if os.path.exists(self._devices_filename):
              log.debug(
                  "loading devices from '{}'...".format(self._devices_filename)
              )
              with codecs.open(self._devices_filename, "rb", "utf-8") as f:
                  self._devices = json.load(f)
  
          return self._devices
docs: load stored devices from the local file