void (final @NotNull PyParenthesizedExpression expression) { final Stack<PsiElement> stack = new Stack<>(); stack.push(expression); while (!stack.isEmpty()) { PsiElement element = stack.pop(); if (!(element instanceof PyTupleExpression)) { findProblem(element); if (element != null) { for (PsiElement psiElement : element.getChildren()) { stack.push(psiElement); } } } } }