Return the same namedtuple that the future module returns

Instead of converting the namedtuple that the future wait
function returns into a normal tuple, just have our own
internal functions use the futures namedtuple directly instead
and avoid any conversion to/from that namedtuple into a normal
tuple.

Change-Id: I54b2595af8d58db60843195034d66a623c20277c

taskflow/utils/async_utils.py

@@ -54,8 +54,9 @@ def wait_for_any(fs, timeout=None):
     """
     green_fs = sum(1 for f in fs if isinstance(f, futures.GreenFuture))
     if not green_fs:
-        return tuple(_futures.wait(fs, timeout=timeout,
-                                   return_when=_futures.FIRST_COMPLETED))
+        return _futures.wait(fs,
+                             timeout=timeout,
+                             return_when=_futures.FIRST_COMPLETED)
     else:
         non_green_fs = len(fs) - green_fs
         if non_green_fs:
@@ -81,9 +82,6 @@ class _GreenWaiter(object):
         self.event.set()
 
 
-def _wait_for_any_green(fs, timeout=None):
-    assert EVENTLET_AVAILABLE, 'eventlet is needed to wait on green futures'
-
 def _partition_futures(fs):
     done = set()
     not_done = set()
@@ -92,12 +90,16 @@ def _wait_for_any_green(fs, timeout=None):
             done.add(f)
         else:
             not_done.add(f)
-        return (done, not_done)
+    return done, not_done
+
+
+def _wait_for_any_green(fs, timeout=None):
+    assert EVENTLET_AVAILABLE, 'eventlet is needed to wait on green futures'
 
     with _base._AcquireFutures(fs):
-        (done, not_done) = _partition_futures(fs)
+        done, not_done = _partition_futures(fs)
         if done:
-            return (done, not_done)
+            return _base.DoneAndNotDoneFutures(done, not_done)
         waiter = _GreenWaiter()
         for f in fs:
             f._waiters.append(waiter)
@@ -107,4 +109,5 @@ def _wait_for_any_green(fs, timeout=None):
         f._waiters.remove(waiter)
 
     with _base._AcquireFutures(fs):
-        return _partition_futures(fs)
+        done, not_done = _partition_futures(fs)
+        return _base.DoneAndNotDoneFutures(done, not_done)