def process_parallel(callbacks, input, *a, **kw):
    """Return a Deferred with the output of all successful calls to the given
    callbacks
    """
    dfds = [defer.succeed(input).addCallback(x, *a, **kw) for x in callbacks]
    d = defer.DeferredList(dfds, fireOnOneErrback=1, consumeErrors=1)
    d.addCallbacks(lambda r: [x[1] for x in r], lambda f: f.value.subFailure)
    return d
Return a Deferred with the output of all successful calls to the given
    callbacks
    
stackoverflow/venv/lib/python3.6/site-packages/scrapy/utils/defer.py