Part of twisted.internet.defer.Deferred View Source
Deferred
.
If the Deferred
has
not yet had its errback
or callback
method
invoked, call the canceller function provided to the constructor. If that
function does not invoke callback
or errback
, or
if no canceller function was provided, errback with CancelledError
.
If this Deferred
is
waiting on another Deferred
,
forward the cancellation to the other Deferred
.