Fix typo

Author: alemazzo

stream/stream.py

@@ -17,7 +17,7 @@ class Stream():
                         .map(lambda w: w.getWeight())
                         .sum()
 
-    A stream pipeline, like the "widgets" example above, can be viewed as a query on the stream source.
+    A stream pipeline, like the elements example above, can be viewed as a query on the stream source.
 
     A stream should be operated on (invoking an intermediate or terminal stream operation) only once. This rules out, for example, "forked" streams, where the same source feeds two or more pipelines, or multiple traversals of the same stream. A stream implementation may raise Exception if it detects that the stream is being reused.
     """