class_docstr: OSS Filesystem Tests
code: def _setup_walk_directories(self, dir_path):
      # Creating a file structure as follows
      # test_dir -> file: file1.txt; dirs: subdir1_1, subdir1_2, subdir1_3
      # subdir1_1 -> file: file3.txt
      # subdir1_2 -> dir: subdir2
      gfile.MkDir(dir_path)
      with gfile.Open(
          file_io.join(dir_path, "file1.txt"), mode="w"
      ) as f:
          f.write("testing")
      sub_dirs1 = ["subdir1_1", "subdir1_2", "subdir1_3"]
      for name in sub_dirs1:
          gfile.MkDir(file_io.join(dir_path, name))
      with gfile.Open(
          file_io.join(dir_path, "subdir1_1/file2.txt"), mode="w"
      ) as f:
          f.write("testing")
      gfile.MkDir(file_io.join(dir_path, "subdir1_2/subdir2"))
  
imports: import os
  import unittest
  from tensorflow.python.framework import errors
  from tensorflow.python.lib.io import file_io
  from tensorflow.python.platform import test
  from tensorflow.python.platform import gfile
  import tensorflow
  import tensorflow_io
label_desc: Use image node_id 27 for calling the OSSFSTest obj's underlying member method code with example usage: obj._setup_walk_directories(dir_path) without return types