'Accrues digits and the plus sign to
_accrued_input_without_formatting for later use. If next_char contains
a digit in non-ASCII format (e.g. the full-width version of digits),
it is first normalized to the ASCII version. The return value is
next_char itself, or its normalized version, if next_char is a digit
in non-ASCII format. This method assumes its input is either a digit
or the plus sign.'

def _normalize_and_accrue_digits_and_plus_sign(self, next_char, remember_position):

    if (next_char == _PLUS_SIGN):
        normalized_char = next_char
        self._accrued_input_without_formatting += next_char
    else:
        next_digit = unicode_digit(next_char, (-1))
        if (next_digit != (-1)):
            normalized_char = unicod(next_digit)
        else:
            normalized_char = next_char
        self._accrued_input_without_formatting += normalized_char
        self._national_number += normalized_char
    if remember_position:
        self._position_to_remember = len(self._accrued_input_without_formatting)
    return normalized_char
