code: def _init(self):
          
          assert self._name
          assert self._group
  
          # self.n = 0
          self.u = []
          self.name = []
          self.idx = []
          self.uid = {}
  
          if not self._unamey:
              self._unamey = self._algebs
          else:
              assert len(self._unamey) == len(self._algebs)
  
          if not self._unamex:
              self._unamex = self._states
          else:
              assert len(self._unamex) == len(self._states)
  
          for item in self._data.keys():
              self.__dict__[item] = []
  
          for bus in self._ac.keys():
              for var in self._ac[bus]:
                  self.__dict__[var] = []
          for node in self._dc.keys():
              for var in self._dc[node]:
                  self.__dict__[var] = []
  
          for var in self._states + self._algebs + self._service:
              self.__dict__[var] = []
  
          self._flags['sysbase'] = False
          self._flags['allocate'] = False
          self._flags['address'] = False
docs: Convert model metadata to class attributes.
  
          This function is called automatically after ``define()`` in new
          versions.
  
          :return: None