@Override
      public void visitPyReferenceExpression(@NotNull PyReferenceExpression node) {
        if (!node.isQualified()) {
          variables.add(node.getReferencedName());
        }
        else {
          super.visitPyReferenceExpression(node);
        }
      }
@Override
      public void visitPyReferenceExpression(@NotNull PyReferenceExpression node)