def METHOD_NAME(self) -> Optional[int]:
    if not self.has_more():
        return None
    ctrl = self.peek()
    if ctrl == "Z":
        self.vidx += 1
        return 0
    if ctrl == "-" or ctrl == "+":
        self.vidx += 1
        offset = self.parse_digits(2) * 60
        self.skip(":")
        offset += self.parse_digits(2)
        offset *= -1 if ctrl == "-" else 1
        return offset
    raise ValueError()