[FIXED] How can I eliminate this error using the websocket library?

Issue

I cobbled together the following code from an example in https://websockets.readthedocs.io/en/stable/intro.html#python-lt-36 This would no doubt be simpler in Python 3.6+, but unfortunately the distro I am using (Raspbian) hosts Python 3.5.3. Clearly, I have done something wrong, but I don't know what. What did I do wrong, and is there a simpler approach?

def my_callback1(channel):  # Down Arrow Pressed
    Return, Cursor = update.upArrow()
    if Return:
        message = "Control, " + str(Cursor)
        asyncio.get_event_loop().run_until_complete(SendMessage(message))

@asyncio.coroutine
def SendMessage(message):
    websocket = yield from websockets.connect('ws://localhost:8000')
    try:
        yield from websocket.send(message)
    finally:
        yield from websocket.close()

GPIO.add_event_detect(pinsarrow[0], GPIO.RISING, callback=my_callback1, bouncetime=bTime)  # Down Arrow

Traceback (most recent call last):
  File "/usr/local/sbin/button.py", line 25, in my_callback1
    asyncio.get_event_loop().run_until_complete(SendMessage(message))
  File "/usr/lib/python3.5/asyncio/events.py", line 671, in get_event_loop
    return get_event_loop_policy().get_event_loop()
  File "/usr/lib/python3.5/asyncio/events.py", line 583, in get_event_loop
    % threading.current_thread().name)
RuntimeError: There is no current event loop in thread 'Dummy-1'.

Solution

Here is the full solution, thanks to shmee:

def my_callback1(channel):  # Down Arrow Pressed
    Return, Cursor = update.downArrow()
    if Return:
        message = "Control, " + str(Cursor)
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        loop.run_until_complete(SendMessage(message))
@asyncio.coroutine
def SendMessage(message):
    websocket = yield from websockets.connect('ws://localhost:8000')
    try:
        yield from websocket.send(message)
    finally:
        yield from websocket.close()

GPIO.add_event_detect(pinsarrow[0], GPIO.RISING, callback=my_callback1, bouncetime=bTime)  # Down Arrow

Answered By - lrhorer