Fix python3 incompatible print in callback docs
@@ -52,7 +52,7 @@ widgets with ``.on_click``, the handler is passed the new attribute value.
.. code-block:: python
def my_radio_handler(new):
- print 'Radio button option ' + str(new) + ' selected.'
+ print('Radio button option ' + str(new) + ' selected.')
radio_group = RadioGroup(labels=["Option 1", "Option 2", "Option 3"], active=0)
radio_group.on_click(my_radio_handler)
