diff --git a/python/psi-api/src/com/jetbrains/python/psi/PyStringLiteralExpression.java b/python/psi-api/src/com/jetbrains/python/psi/PyStringLiteralExpression.java
index 550fa8c3a2b9..49b8368245a0 100644
--- a/python/psi-api/src/com/jetbrains/python/psi/PyStringLiteralExpression.java
+++ b/python/psi-api/src/com/jetbrains/python/psi/PyStringLiteralExpression.java
@@ -15,7 +15,18 @@ public interface PyStringLiteralExpression extends PyLiteralExpression, StringLi
 
   void iterateCharacterRanges(TextRangeConsumer consumer);
 
+  /**
+   * Iterator over decoded string characters.
+   */
   interface TextRangeConsumer {
+    /**
+     * Process a decoded character.
+     *
+     * @param startOffset start offset in the un-decoded string
+     * @param endOffset end offset in the un-decoded string
+     * @param value decoded character value
+     * @return false in order to stop iteration
+     */
     boolean process(int startOffset, int endOffset, String value);
   }
 }