code: def test_escape_token(self):
      escaped = text_encoder._escape_token(
          "Foo! Bar.\nunder_score back\\slash",
          set("abcdefghijklmnopqrstuvwxyz .\n")
          | text_encoder._ESCAPE_CHARS,
      )
  
      self.assertEqual(
          "\\70;oo\\33; \\66;ar.\\10;under\\uscore back\\\\slash_",
          escaped,
      )
  
imports: import collections
  import io
  import os
  import random
  import shutil
  import string
  import mock
  from six.moves import range
  import tensorflow.compat.v1
  from trax.data import text_encoder
label_desc: Use image node_id 1 for calling the EscapeUnescapeTokenTest obj's underlying member method code with example usage: obj.test_escape_token() without return types