Python 3 compatibility in doc/conf.py

doc/conf.py

@@ -256,13 +256,13 @@ intersphinx_mapping = {'http://docs.python.org/': None}
 # fall back if theme is not there
 try:
     __import__('flask_theme_support')
-except ImportError, e:
-    print '-' * 74
-    print 'Warning: Flask themes unavailable. Building with default theme'
-    print 'If you want the Flask themes, run this command and build again:'
-    print
-    print ' git submodule update --init'
-    print '-' * 74
+except ImportError as e:
+    print('-' * 74)
+    print('Warning: Flask themes unavailable. Building with default theme')
+    print('If you want the Flask themes, run this command and build again:')
+    print()
+    print(' git submodule update --init')
+    print('-' * 74)
 
     pygments_style = 'tango'
     html_theme = 'default'