add missing info from groupby documentation

Change-Id: Icfaf242353c23a579fe79f9d72500a08d90fcb77
Signed-off-by: Federico Caselli <cfederico87@gmail.com>

diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index ebe8bb0e1c376082dd8a578f9793ce9349213377..8013477fa98cf4eb3b56cf1d8dfe709357a8bf2f 100644 (file)
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -3819,6 +3819,8 @@ class GenerativeSelect(DeprecatedSelectBaseGenerations, SelectBase):
         r"""Return a new selectable with the given list of GROUP BY
         criterion applied.
 
+        All existing GROUP BY settings can be suppressed by passing ``None``.
+
         e.g.::
 
             stmt = select(table.c.name, func.max(table.c.stat)).\