How should we send notifications to multiple tokens with the updated API?

[sgserg]

Attempting to use async_notify_multiple_devices yields

Traceback (most recent call last):
   ...
   ...
  File "/usr/local/lib/python3.6/dist-packages/pyfcm/fcm.py", line 81, in async_notify_multiple_devices
    return self.send_async_request(payloads=payloads, timeout=timeout)
TypeError: send_async_request() got an unexpected keyword argument 'payloads'