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

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)