code: def get_grapheme_character_set(
      locale: str, case: str = "upper"
  ) -> str:
      if locale not in GRAPHEME_CHARACTER_SETS:
          raise ValueError(
              f"Grapheme character set not found for locale '{locale}'. "
              f"Supported locales {GRAPHEME_CHARACTER_SETS.keys()}"
          )
  
      charset_str_origin = "".join(GRAPHEME_CHARACTER_SETS[locale])
      if case == "upper":
          # Directly call .upper() will convert 'ß' into 'SS' according to https://bugs.python.org/issue30810.
          charset_str = charset_str_origin.replace("ß", "ẞ").upper()
      elif case == "lower":
          charset_str = charset_str_origin.lower()
      elif case == "mixed":
          charset_str = (
              charset_str_origin.replace("ß", "ẞ").upper()
              + charset_str_origin.lower()
          )
      else:
          raise ValueError(
              f"Grapheme character case not found: '{case}'. Supported cases are {GRAPHEME_CHARACTER_CASES}"
          )
  
      return charset_str
  
label_desc: Use image node_id 2 for calling a global function with example usage: get_grapheme_character_set(locale, case) and returns: charset_str