void (@Nullable final PsiElement expression) { final PsiWhiteSpace[] children = PsiTreeUtil.getChildrenOfType(expression, PsiWhiteSpace.class); if (children != null) { for (PsiWhiteSpace ws : children) { if (ws.getText().contains("\\")) { registerProblem(ws, PyPsiBundle.message("INSP.unnecessary.backslash.unnecessary.backslash.in.expression"), new RemoveUnnecessaryBackslashQuickFix()); } } } }