Class PostWalkRulesException

                                   object --+            
                                            |            
                     exceptions.BaseException --+        
                                                |        
                             exceptions.Exception --+    
                                                    |    
exception.device_atlas_exception.DeviceAtlasException --+
                                                        |
                                                       PostWalkRules.PostWalkRulesException

The PostWalkRulesException exception is raised by this class when the init_get_matcher_propery_ids() or init_rule_sets() are called before they have been replaced by any new implementation from a child class. This helps us to simulate abstract methods, which does not exist in Ruby.