docstr: A file already at version 3 should stay at version 3.
docstr_tok: ["A","file","already","at","version","3","should","stay","at","version","3","."]
code: def testAlreadyUpgraded(self):
      """A file already at version 3 should stay at version 3."""
      self.CheckConversion(EMPTY_TEST_SCHEMA_V3, EMPTY_TEST_SCHEMA_V3)
      self.CheckConversion(TEST_SCHEMA_V3, TEST_SCHEMA_V3)
      self.CheckConversion(BUFFER_TEST_V3, BUFFER_TEST_V3)
  
file_path: tensorflow/tensorflow/lite/schema/upgrade_schema_test.py
imports: import json
  import tempfile
  from tensorflow.lite.schema import upgrade_schema
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import test
label_desc: Use image node_id 4 for calling the TestSchemaUpgrade obj's underlying member method code with example usage: obj.testAlreadyUpgraded() without return types