@Override
    public void visitPyReferenceExpression(final @NotNull PyReferenceExpression node) {
      String referencedName = node.getReferencedName();
      if (PyNames.NONE.equals(referencedName)) {
        //noinspection DialogTitleCapitalization
        getHolder().newAnnotation(HighlightSeverity.ERROR, (myOp == Operation.Delete) ?
                                                           message("ANN.deleting.none") :
                                                           message("ANN.assign.to.none")).range(node).create();
      }
    }
@Override
    public void visitPyReferenceExpression(final @NotNull PyReferenceExpression node)