diff --git a/platform/syntax/syntax-api/src/com/intellij/platform/syntax/impl/builder/CharSequenceSubSequence.kt b/platform/syntax/syntax-api/src/com/intellij/platform/syntax/impl/builder/CharSequenceSubSequence.kt
index a141a58163a2..8a0590ae28f1 100644
--- a/platform/syntax/syntax-api/src/com/intellij/platform/syntax/impl/builder/CharSequenceSubSequence.kt
+++ b/platform/syntax/syntax-api/src/com/intellij/platform/syntax/impl/builder/CharSequenceSubSequence.kt
@@ -33,5 +33,5 @@ internal class CharSequenceSubSequence(chars: CharSequence, start: Int, end: Int
   }
 
   override fun toString(): String =
-    throw UnsupportedOperationException("Not supported yet")
+    throw UnsupportedOperationException("Not supported yet") // TODO?
 }
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