bpo-40025: Require _generate_next_value_ to be defined before members(GH-19763)
require `_generate_next_value_` to be defined before members
diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst
index 7538084..2649b7d 100644
--- a/Doc/library/enum.rst
+++ b/Doc/library/enum.rst
@@ -273,6 +273,10 @@
the next :class:`int` in sequence with the last :class:`int` provided, but
the way it does this is an implementation detail and may change.
+.. note::
+
+ The :meth:`_generate_next_value_` method must be defined before any members.
+
Iteration
---------