You can clone with
from twisted.internet import reactor, defer, task
def read_input_status(address, length, callback):
print 'Before assertion.'
print 'After assertion'
d = defer.Deferred()
d = task.deferLater(reactor, 1, read_input_status, 0x0000, 8, None)
The question here is: why is the errback not called in case of the failing assertion?
Reason: my_callback and my_errback are lacking a required single argument to receive the result or failure of the asynchronous call respectively.