Python 2 bugfix in switch-between-vi-emacs example.

2 files changed, 2 insertions, 1 deletions

diff --git a/examples/prompts/switch-between-vi-emacs.py b/examples/prompts/switch-between-vi-emacs.py
index 533c92fc..dc0edd8d 100755
--- a/examples/prompts/switch-between-vi-emacs.py
+++ b/examples/prompts/switch-between-vi-emacs.py
@@ -3,6 +3,7 @@
 Example that displays how to switch between Emacs and Vi input mode.
 
 """
+from __future__ import unicode_literals
 from prompt_toolkit import prompt
 from prompt_toolkit.application.current import get_app
 from prompt_toolkit.enums import EditingMode
diff --git a/prompt_toolkit/key_binding/key_bindings.py b/prompt_toolkit/key_binding/key_bindings.py
index 0941ab20..e3af537a 100644
--- a/prompt_toolkit/key_binding/key_bindings.py
+++ b/prompt_toolkit/key_binding/key_bindings.py
@@ -331,7 +331,7 @@ def _check_and_expand_key(key):
         key = ' '
 
     # Final validation.
-    assert isinstance(key, text_type)
+    assert isinstance(key, text_type), 'Got %r' % (key, )
     if len(key) != 1 and key not in ALL_KEYS:
         raise ValueError('Invalid key: %s' % (key, ))