code: def test_character_tokenize_index():
      sr = cudf.core.index.as_index(
          [
              "hello world",
              "sdf",
              None,
              (
                  "goodbye, one-two:three~four+five_six@sev"
                  "en#eight^nine heŒŽ‘•™œ$µ¾ŤƠé Ǆ"
              ),
          ]
      )
      expected = cudf.core.index.as_index(
          [
              "h",
              "e",
              "l",
              "l",
              "o",
              " ",
              "w",
              "o",
              "r",
              "l",
              "d",
              "s",
              "d",
              "f",
              "g",
              "o",
              "o",
              "d",
              "b",
              "y",
              "e",
              ",",
              " ",
              "o",
              "n",
              "e",
              "-",
              "t",
              "w",
              "o",
              ":",
              "t",
              "h",
              "r",
              "e",
              "e",
              "~",
              "f",
              "o",
              "u",
              "r",
              "+",
              "f",
              "i",
              "v",
              "e",
              "_",
              "s",
              "i",
              "x",
              "@",
              "s",
              "e",
              "v",
              "e",
              "n",
              "#",
              "e",
              "i",
              "g",
              "h",
              "t",
              "^",
              "n",
              "i",
              "n",
              "e",
              " ",
              "h",
              "e",
              "Œ",
              "Ž",
              "‘",
              "•",
              "™",
              "œ",
              "$",
              "µ",
              "¾",
              "Ť",
              "Ơ",
              "é",
              " ",
              "Ǆ",
          ]
      )
  
      actual = sr.str.character_tokenize()
      assert_eq(expected, actual)
  
      sr = cudf.Index([""])
      expected = cudf.Index([], dtype="object")
  
      actual = sr.str.character_tokenize()
      assert_eq(expected, actual)
  
      sr = cudf.core.index.as_index(["a"])
      expected = cudf.core.index.as_index(["a"])
  
      actual = sr.str.character_tokenize()
      assert_eq(expected, actual)
  
imports: import random
  import string
  import numpy
  import pytest
  import cudf
  from cudf.core.byte_pair_encoding import BytePairEncoder
  from cudf.core.tokenize_vocabulary import TokenizeVocabulary
  from cudf.testing._utils import assert_eq
label_desc: Use image node_id 13 for calling a global function with example usage: test_character_tokenize_index() without return types