Recipe package system.

recipe_engine/third_party/setuptools/_vendor/packaging/_compat.py

+# Copyright 2014 Donald Stufft
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import, division, print_function
+
+import sys
+
+
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+
+# flake8: noqa
+
+if PY3:
+    string_types = str,
+else:
+    string_types = basestring,
+
+
+def with_metaclass(meta, *bases):
+    """
+    Create a base class with a metaclass.
+    """
+    # This requires a bit of explanation: the basic idea is to make a dummy
+    # metaclass for one level of class instantiation that replaces itself with
+    # the actual metaclass.
+    class metaclass(meta):
+        def __new__(cls, name, this_bases, d):
+            return meta(name, bases, d)
+    return type.__new__(metaclass, 'temporary_class', (), {})