Asynchronous method call in Python?

I was wondering if there’s any library for asynchronous method calls in Python. It would be great if you could do something like

@async
def longComputation():
    <code>


token = longComputation()
token.registerCallback(callback_function)
# alternative, polling
while not token.finished():
    doSomethingElse()
    if token.finished():
        result = token.result()

Or to call a non-async routine asynchronously

def longComputation()
    <code>

token = asynccall(longComputation())

It would be great to have a more refined strategy as native in the language core. Was this considered?