code: def _alloc(self):
          
          nzeros = [0] * self.n
          for var in self._states:
              self.__dict__[var] = nzeros[:]
          for var in self._algebs:
              self.__dict__[var] = nzeros[:]
docs: Allocate empty memory for dae variable indices.
          Called in device setup phase.
  
          :return: None