code: def test_insert_zero_width_chars(self) -> None:
      augmented_every_char = txtaugs.insert_zero_width_chars(
          self.texts, "all", 1.0, False
      )
      # Separator inserted between every character (including spaces/punctuation).
      # Renders as: "T‌h‌e‌ ‌q‌u‌i‌c‌k‌ ‌b‌r‌o‌w‌n‌ ‌'‌f‌o‌x‌'‌ ‌c‌o‌u‌l‌d‌n‌'‌t‌ ‌j‌u‌m‌p‌ ‌o‌v‌e‌r‌ ‌t‌h‌e‌ ‌g‌r‌e‌e‌n‌,‌ ‌g‌r‌a‌s‌s‌y‌ ‌h‌i‌l‌l‌."
      self.assertEqual(
          augmented_every_char,
          [
              "T\u200bh\u200be\u200b \u200bq\u200bu\u200bi\u200bc\u200bk\u200b "
              "\u200bb\u200br\u200bo\u200bw\u200bn\u200b \u200b'\u200bf\u200bo"
              "\u200bx\u200b'\u200b \u200bc\u200bo\u200bu\u200bl\u200bd\u200bn"
              "\u200b'\u200bt\u200b \u200bj\u200bu\u200bm\u200bp\u200b \u200bo"
              "\u200bv\u200be\u200br\u200b \u200bt\u200bh\u200be\u200b \u200bg"
              "\u200br\u200be\u200be\u200bn\u200b,\u200b \u200bg\u200br\u200ba"
              "\u200bs\u200bs\u200by\u200b \u200bh\u200bi\u200bl\u200bl\u200b."
          ],
      )
      augmented_per_word = txtaugs.insert_zero_width_chars(
          self.texts, "word", 1.0, False
      )
      # Each word uses a different separator; no separators around whitespace.
      # Renders as: "T⁡h⁡e q‌u‌i‌c‌k b⁣r⁣o⁣w⁣n '⁡f⁡o⁡x⁡' c‌o‌u‌l‌d‌n‌'‌t j​u​m​p o⁣v⁣e⁣r t⁢h⁢e g⁢r⁢e⁢e⁢n⁢, g​r​a​s​s​y h‍i‍l‍l‍."
      self.assertEqual(
          augmented_per_word,
          [
              "T\u2061h\u2061e q\u200cu\u200ci\u200cc\u200ck b\u2063r\u2063o"
              "\u2063w\u2063n '\u2061f\u2061o\u2061x\u2061' c\u200co\u200cu"
              "\u200cl\u200cd\u200cn\u200c'\u200ct j\u200bu\u200bm\u200bp o"
              "\u2063v\u2063e\u2063r t\u2062h\u2062e g\u2062r\u2062e\u2062e"
              "\u2062n\u2062, g\u200br\u200ba\u200bs\u200bs\u200by h\u200di"
              "\u200dl\u200dl\u200d."
          ],
      )
      augmented_wider_cadence = txtaugs.insert_zero_width_chars(
          self.texts, "all", 2.7, False
      )
      # Separators are every 2-3 (avg. 2.7) characters.
      # Renders as: "The‍ qu‍ick‍ b‍row‍n '‍fo‍x' ‍cou‍ld‍n't‍ ju‍mp ‍ov‍er ‍the‍ g‍ree‍n, ‍gr‍ass‍y h‍ill‍."
      self.assertEqual(
          augmented_wider_cadence,
          [
              "The\u200d qu\u200dick\u200d b\u200drow\u200dn '\u200dfo\u200dx"
              "' \u200dcou\u200dld\u200dn't\u200d ju\u200dmp \u200dov\u200der"
              " \u200dthe\u200d g\u200dree\u200dn, \u200dgr\u200dass\u200dy h"
              "\u200dill\u200d."
          ],
      )
      augmented_varying_char = txtaugs.insert_zero_width_chars(
          self.texts, "all", 2.0, True
      )
      # Each separator is chosen independently.
      # Renders as: "Th‍e ‍qu‌ic​k ⁠br​ow⁡n ​'f‍ox⁠' ⁤co​ul‌dn⁣'t​ j⁤um⁡p ‍ov⁣er⁣ t‍he⁣ g‌re⁡en⁡, ⁣gr‍as⁠sy⁣ h⁡il⁢l."
      self.assertEqual(
          augmented_varying_char,
          [
              "Th\u200de \u200dqu\u200cic\u200bk \u2060br\u200bow\u2061n \u200b"
              "'f\u200dox\u2060' \u2064co\u200bul\u200cdn\u2063't\u200b j\u2064u"
              "m\u2061p \u200dov\u2063er\u2063 t\u200dhe\u2063 g\u200cre\u2061e"
              "n\u2061, \u2063gr\u200das\u2060sy\u2063 h\u2061il\u2062l."
          ],
      )
  
imports: import random
  import unittest
  from augly import text
  from augly.utils import FUN_FONTS_GREEK_PATH
label_desc: Use image node_id 10 for calling the FunctionalTextUnitTest obj's underlying member method code with example usage: obj.test_insert_zero_width_chars() without return types