Clarify what operations the default Undefined supports

diff --git a/src/jinja2/runtime.py b/src/jinja2/runtime.py
index 53582ae8bc742673eeeaacbf54e60a62a8b2bf05..d10fe9d06e3afdbe21c9670c2a645e7f00e1e94c 100644 (file)
--- a/src/jinja2/runtime.py
+++ b/src/jinja2/runtime.py
@@ -792,8 +792,8 @@ class Macro:
 
 
 class Undefined:
-    """The default undefined type.  This undefined type can be printed and
-    iterated over, but every other access will raise an :exc:`UndefinedError`:
+    """The default undefined type. This can be printed, iterated, and treated as
+    a boolean. Any other operation will raise an :exc:`UndefinedError`.
 
     >>> foo = Undefined(name='foo')
     >>> str(foo)