docstr: Move the already generated _metadata to a different name, leveraging tempdir uniqueness. 
docstr_tok: ["Move","the","already","generated","_metadata","to","a","different","name",",","leveraging","tempdir","uniqueness","."]
code: def vanish_metadata(self, filename="_common_metadata"):
      """Move the already generated _metadata to a different name, leveraging tempdir uniqueness."""
      move(
          "{}/{}".format(self._dataset_dir, filename),
          "{}{}".format(self._dataset_dir, filename + "_gone"),
      )
  
file_path: petastorm/petastorm/tests/test_metadata_read.py
imports: import os
  import unittest
  from shutil import move, rmtree
  from tempfile import mkdtemp
  from petastorm.tests.test_common import create_test_dataset
label_desc: Use image node_id 3 for calling the MetadataUnischemaReadTest obj's underlying member method code with example usage: obj.vanish_metadata(filename) without return types