code: def test_token_stats(self):
      from parlai.scripts.token_stats import TokenStats
      from parlai.core.metrics import dict_report
  
      results = dict_report(
          TokenStats.main(task="integration_tests:multiturn")
      )
      assert results == {
          "exs": 2000,
          "max": 16,
          "mean": 7.5,
          "min": 1,
          "p01": 1,
          "p05": 1,
          "p10": 1,
          "p25": 4,
          "p50": 7.5,
          "p75": 11.5,
          "p90": 16,
          "p95": 16,
          "p99": 16,
          "p@128": 1,
      }
  
imports: import os
  import unittest
  from parlai.core.message import Message
  from parlai.core.mutators import MessageMutator, register_mutator
  import parlai.utils.testing
label_desc: Use image node_id 1 for calling the TestTokenStats obj's underlying member method code with example usage: obj.test_token_stats() without return types