public function setLastDigits( $lastDigits )
    {
        $lastDigits = trim( $lastDigits );

        if (strlen( $lastDigits ) !== 4) {
            throw new InvalidArgumentException( sprintf( 'Last digits should contain the last 4 characters in the card number (%s)',
                $lastDigits ) );
        }

        $this->lastDigits = $lastDigits;

        return $this;
    }
public function setLastDigits( $lastDigits )
    {
        $lastDigits = trim( $lastDigits );

        if (strlen( $lastDigits ) !== 4) {
            throw new InvalidArgumentException( sprintf( 'Last digits should contain the last 4 characters in the card number (%s)',
                $lastDigits ) );
        }

        $this->lastDigits = $lastDigits;

        return $this;
    }
@param  string $lastDigits

@return $this