+ """Await the completion of any of a collection of SmartFutures and
+ invoke callback each time one completes, repeatedly, until they are
+ all finished.
+
+ Args:
+ futures: A collection of SmartFutures to wait on
+ callback: An optional callback to invoke whenever one of the
+ futures completes
+ log_exceptions: Should we log (warning + exception) any
+ underlying exceptions raised during future processing or
+ silently ignore then?
+ """
+