docs: def hexify(self, text='^^^^', upper=False):
          """
          Replaces all circumflex ('^') occurrences with a random
          hexadecimal character.
  
          :param text: string to be parsed
          :param upper: Format as uppercase hexadecimal
          :returns: string with all letter placeholders filled in
          """
          letters = string.hexdigits[:-6]
          if upper:
              letters = letters.upper()
          return _re_cir.sub(lambda x: self.random_element(letters), text)