code: def peek_step(self, val: ArrayValue,
                    sn: "DataNode") -> Tuple[Value, "DataNode"]:
          
          try:
              return (val[val.index(self.parse_value(sn))], sn)
          except ValueError:
              return None, sn
docs: Return entry value addressed by the receiver + its schema node.
  
          Args:
              val: Current value (array).
              sn:  Current schema node.