Extracts IDD and plus sign to self._prefix_before_national_number
        when they are available, and places the remaining input into
        _national_number.

        Returns True when accrued_input_without_formatting begins with the plus sign or valid IDD for
        default_country.

def _attempt_to_extract_idd(self):
        """Extracts IDD and plus sign to self._prefix_before_national_number
        when they are available, and places the remaining input into
        _national_number.

        Returns True when accrued_input_without_formatting begins with the plus sign or valid IDD for
        default_country.
        """
        international_prefix = re.compile(unicod("\\") + _PLUS_SIGN + unicod("|") +
                                          (self._current_metadata.international_prefix or U_EMPTY_STRING))
        idd_match = international_prefix.match(self._accrued_input_without_formatting)
        if idd_match:
            self._is_complete_number = True
            start_of_country_calling_code = idd_match.end()
            self._national_number = self._accrued_input_without_formatting[start_of_country_calling_code:]
            self._prefix_before_national_number = self._accrued_input_without_formatting[:start_of_country_calling_code]
            if self._accrued_input_without_formatting[0] != _PLUS_SIGN:
                self._prefix_before_national_number += _SEPARATOR_BEFORE_NATIONAL_NUMBER
            return True
        return False