print() is a function in Python 3

Like #2740 but for the docs

Signed-off-by: Christian Clauss <[email protected]>

Author: cclauss

docs/index.rst

@@ -58,7 +58,7 @@ You can stream logs:
 .. code-block:: python
 
   >>> for line in container.logs(stream=True):
-  ...   print line.strip()
+  ...   print(line.strip())
   Reticulating spline 2...
   Reticulating spline 3...
   ...