Use func

Author: savannahostrowski

Doc/whatsnew/3.14.rst

@@ -421,7 +421,7 @@ Deprecated
 ==========
 
 * :mod:`argparse`:
-  Passing *prefix_chars* to :meth:`argparse.add_argument_group`
+  Passing *prefix_chars* to :func:`argparse.add_argument_group`
   is now deprecated.
   (Contributed by Savannah Ostrowski in :gh:`125563`.)