Changed print to use the function syntax.

docs/examples/lib/gui-gtk3.py

@@ -1,37 +1,37 b''
 #!/usr/bin/env python
 """Simple Gtk example to manually test event loop integration.
 
 This is meant to run tests manually in ipython as:
 
 In [1]: %gui gtk3
 
 In [2]: %run gui-gtk3.py
 """
 
 from gi.repository import Gtk
 
 
 def hello_world(wigdet, data=None):
-    print "Hello World"
+    print("Hello World")
 
 def delete_event(widget, event, data=None):
     return False
 
 def destroy(widget, data=None):
     Gtk.main_quit()
 
 window = Gtk.Window(Gtk.WindowType.TOPLEVEL)
 window.connect("delete_event", delete_event)
 window.connect("destroy", destroy)
 button = Gtk.Button("Hello World")
 button.connect("clicked", hello_world, None)
 
 window.add(button)
 button.show()
 window.show()
 
 try:
     from IPython.lib.inputhook import enable_gtk3
     enable_gtk3()
 except ImportError:
     Gtk.main()