code: def testGenerateShardedFilenamesManyShards(self):
      names = io.generate_sharded_filenames("/dir/foo/bar@100000")
      self.assertEqual(len(names), 100000)
      self.assertEqual(names[99999], "/dir/foo/bar-099999-of-100000")
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import absltest
  from absl.testing import parameterized
  from third_party.nucleus.io import sharded_file_utils
  from third_party.nucleus.testing import test_utils
label_desc: Use image node_id 4 for calling the ShardsTest obj's underlying member method code with example usage: obj.testGenerateShardedFilenamesManyShards() without return types