code: def _set_internal_value(self, new_internal_value):
          
  
          if new_internal_value != self._internal_value:
  
              self._internal_value = new_internal_value
  
              # Call callbacks if any
  
              for callback in self._callbacks:
  
                  callback(self)
docs: This is supposed to be only used by fitting engines
  
          :param new_internal_value: new value in internal representation
          :return: none