code: def peek_step(self, val: ObjectValue,
                    sn: "DataNode") -> Tuple[Value, "DataNode"]:
          
          cn = sn.get_data_child(self.name, self.namespace)
          try:
              return (val[cn.iname()], cn)
          except (IndexError, KeyError, TypeError):
              return (None, cn)
docs: Return member value addressed by the receiver + its schema node.
  
          Args:
              val: Current value (object).
              sn:  Current schema node.