[python] readonly constructors (#9409)

* readonly

* other tests

* doc

* python samples

* model utils

samples/openapi3/client/petstore/python/test/test_mole.py

@@ -0,0 +1,35 @@
+"""
+    OpenAPI Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+import sys
+import unittest
+
+import petstore_api
+from petstore_api.model.mole import Mole
+
+
+class TestMole(unittest.TestCase):
+    """Mole unit test stubs"""
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def testMole(self):
+        """Test Mole"""
+        # FIXME: construct object with mandatory attributes with example values
+        # mole = Mole()  # noqa: E501
+        pass
+
+
+if __name__ == '__main__':
+    unittest.main()