TOTP/TOTPTimeManager.php
public function setStampLength($stampLength = null)
    {
        if ($stampLength === null) {
            $stampLength = self::DEFAULT_STAMP_LENGTH;
        }
        $stampLength = intval($stampLength);
        if (empty($stampLength) || $stampLength < 0) {
            throw new InvalidArgumentException('Stamp length must be greater than 0 and positive.');
        }
        $this->stampLength = $stampLength;

        return $this;
    }
public function setStampLength($stampLength = null)
    {
        if ($stampLength === null) {
            $stampLength = self::DEFAULT_STAMP_LENGTH;
        }
        $stampLength = intval($stampLength);
        if (empty($stampLength) || $stampLength < 0) {
            throw new InvalidArgumentException('Stamp length must be greater than 0 and positive.');
        }
        $this->stampLength = $stampLength;

        return $this;
    }
@param int|null $stampLength Length of a unit time (default 30)

@return TOTPTimeManager