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diff --git a/tensorflow/core/lib/io/two_level_iterator.h b/tensorflow/core/lib/io/two_level_iterator.h
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+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef TENSORFLOW_LIB_IO_TWO_LEVEL_ITERATOR_H_
+#define TENSORFLOW_LIB_IO_TWO_LEVEL_ITERATOR_H_
+
+#include "tensorflow/core/lib/io/iterator.h"
+
+namespace tensorflow {
+namespace table {
+
+// Return a new two level iterator.  A two-level iterator contains an
+// index iterator whose values point to a sequence of blocks where
+// each block is itself a sequence of key,value pairs.  The returned
+// two-level iterator yields the concatenation of all key/value pairs
+// in the sequence of blocks.  Takes ownership of "index_iter" and
+// will delete it when no longer needed.
+//
+// Uses a supplied function to convert an index_iter value into
+// an iterator over the contents of the corresponding block.
+extern Iterator* NewTwoLevelIterator(
+    Iterator* index_iter,
+    Iterator* (*block_function)(void* arg, const StringPiece& index_value),
+    void* arg);
+
+}  // namespace table
+}  // namespace tensorflow
+
+#endif  // TENSORFLOW_LIB_IO_TWO_LEVEL_ITERATOR_H_