in inject/inject-utils/src/main/scala/com/twitter/inject/conversions/future.scala [205:214]
def partialTransform(pf: PartialFunction[Try[A], Future[A]]): Future[A] = {
self.transform {
case ret @ Return(r) if pf.isDefinedAt(ret) =>
pf(ret)
case thr @ Throw(t) if pf.isDefinedAt(thr) =>
pf(thr)
case _ =>
self
}
}