'Mangle the digits (if any) in the fr URL.
:param fuzzable_request: The original FuzzableRequest
:return: A generator which returns mangled fuzzable requests'

def _mangle_digits(self, fuzzable_request):

    filename = fuzzable_request.get_url().get_file_name()
    domain_path = fuzzable_request.get_url().get_domain_path()
    for fname in self._do_combinations(filename):
        fr_copy = copy.deepcopy(fuzzable_request)
        fr_copy.set_url(domain_path.url_join(fname))
        if (fr_copy.get_uri() not in self._already_visited):
            self._already_visited.add(fr_copy.get_uri())
            (yield fr_copy)
    data_container = fuzzable_request.get_querystring()
    for (_, token) in data_container.iter_bound_tokens():
        for modified_value in self._do_combinations(token.get_value()):
            fr_copy = copy.deepcopy(fuzzable_request)
            qs = fr_copy.get_querystring()
            qs_token = qs.set_token(token.get_path())
            qs_token.set_value(modified_value)
            if (fr_copy.get_uri() not in self._already_visited):
                self._already_visited.add(fr_copy.get_uri())
                (yield fr_copy)
