--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/thirdparty/zope/interface/_flatten.py	Wed Mar 21 19:48:50 2018 -0700
@@ -0,0 +1,35 @@
+##############################################################################
+#
+# Copyright (c) 2002 Zope Foundation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""Adapter-style interface registry
+
+See Adapter class.
+"""
+from zope.interface import Declaration
+
+def _flatten(implements, include_None=0):
+
+    try:
+        r = implements.flattened()
+    except AttributeError:
+        if implements is None:
+            r=()
+        else:
+            r = Declaration(implements).flattened()
+
+    if not include_None:
+        return r
+
+    r = list(r)
+    r.append(None)
+    return r