'Cancel this L{DeferredList}.
If the L{DeferredList} hasn\'t fired yet, cancel every L{Deferred} in
the list.
If the L{DeferredList} has fired, including the case where the
C{fireOnOneCallback}/C{fireOnOneErrback} flag is set and the
L{DeferredList} fires because one L{Deferred} in the list fires with a
non-failure/failure result, do nothing in the C{cancel} method.'

def cancel(self):

    if (not self.called):
        for deferred in self._deferredList:
            try:
                deferred.cancel()
            except:
                log.failure('Exception    raised    from    user    supplied    canceller')
