class_docstr: OSS Filesystem Tests
code: def test_tell(self):
      file_path = file_io.join(self._base_dir, "temp_file")
      with gfile.Open(file_path, mode="r+") as f:
          f.write("testing1\ntesting2\ntesting3\n\ntesting5")
      self.assertEqual(0, f.tell())
      self.assertEqual("testing1\n", f.readline())
      self.assertEqual(9, f.tell())
      self.assertEqual("testing2\n", f.readline())
      self.assertEqual(18, f.tell())
      self.assertEqual("testing3\n", f.readline())
      self.assertEqual(27, f.tell())
      self.assertEqual("\n", f.readline())
      self.assertEqual(28, f.tell())
      self.assertEqual("testing5", f.readline())
      self.assertEqual(36, f.tell())
      self.assertEqual("", f.readline())
      self.assertEqual(36, f.tell())
  
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 35 for calling the OSSFSTest obj's underlying member method code with example usage: obj.test_tell() without return types