anchor.diff:          procedure :: remove_by_pointer !! remove node given pointer
           procedure :: get_node          !! get a pointer to a node in the list
           procedure :: keys_equal        !! for testing key string equality
  +
  +        final :: list_finalizer
   
       end type list
   
  
positive.code:     nullify(me%value)
  
      end subroutine destroy_node_data
  !*****************************************************************************************
  
  !*****************************************************************************************
  
negative.code: !*****************************************************************************************
  
  !*****************************************************************************************
      pure function keys_equal(me,k1,k2)
  
      !! Returns true if the two keys are equal.
      !!
  