class_docstr: CMVN unittest Class
docstr: tear down 
docstr_tok: ["tear","down"]
code: def tearDown(self):
      """tear down"""
  
file_path: delta/delta/utils/cmvn_test.py
imports: import os
  import numpy
  import delta.compat
  from delta import utils
label_desc: Use image node_id 2 for calling the CmvnTest obj's underlying member method code with example usage: obj.tearDown() without return types