human
Solve the following python programming problem given the following code:
@ mock.patch.object (build_request.BuildRequest, '_create_in_db') 
def test_create(self, create_in_db) : 
    fake_req = fake_build_request.fake_db_req () 
    req_obj = fake_build_request.fake_req_obj (self.context, fake_req) 
    def _test_create_args(self2, context, changes) : 
        for field in [fields for fields in build_request.BuildRequest.fields if (fields not in ['created_at', 'updated_at', 'request_spec', 'id'])] : 
            self.assertEqual (fake_req [field], changes [field]) 
self.assertEqual (fake_req ['request_spec'] ['id'], changes ['request_spec_id']) 
        self.assertEqual (jsonutils.dumps (req_obj.instance.obj_to_primitive ()), changes ['instance']) 
        return fake_req 
with mock.patch.object (build_request.BuildRequest, '_create_in_db', <MASK>) : 
        req_obj.create () 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: req_obj, create_in_db, self, fake_req
assistant
#Here is a proper replacement for <MASK>.
def _test_create_args(