add note about flatten function (one already exists in nmigen)

diff --git a/src/nmutil/util.py b/src/nmutil/util.py
index b6a8d196d1ac67d5b47b092fdf2c726659605d64..e0b09af164c27b6dd64c32e8cc6402ce0a647db4 100644 (file)
--- a/src/nmutil/util.py
+++ b/src/nmutil/util.py
@@ -1,6 +1,7 @@
 from collections.abc import Iterable
 
-
+# XXX this already exists in nmigen._utils
+# see https://bugs.libre-soc.org/show_bug.cgi?id=297
 def flatten(v):
     if isinstance(v, Iterable):
         for i in v: