+# This file is Free Software. It was originally written for secnet.
+#
+# Copyright 2014 Ian Jackson
+#
+# You may redistribute secnet as a whole and/or modify it under the
+# terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any
+# later version.
+#
+# You may redistribute this fileand/or modify it under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2, or (at your option) any later version.
+#
+# This software is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this software; if not, see
+# https://www.gnu.org/licenses/gpl.html.
+#
+# The corresponding test vector file ise ipaddrset-test.expected. I
+# don't believe it is a creative work that attracts copyright. -iwj.
+
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import ipaddress
+from ipaddress import ip_network, ip_address