Added __all__.
diff --git a/Lib/heapq.py b/Lib/heapq.py
index 15b728a..fd7eea5 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -126,6 +126,8 @@
 From all times, sorting has always been a Great Art! :-)
 """
 
+__all__ = ['heappush', 'heappop', 'heapify', 'heapreplace']
+
 def heappush(heap, item):
     """Push item onto heap, maintaining the heap invariant."""
     heap.append(item)