public function setSequential( $sequential )
    {
        if (preg_match( '/^[1-9]$/', $sequential ) !== 1) {
            throw new InvalidArgumentException( sprintf( 'Sequential number should be between 1 and 9 (%s)',
                $sequential ) );
        }

        $this->sequential = intval( $sequential );

        return $this;
    }
public function setSequential( $sequential )
    {
        if (preg_match( '/^[1-9]$/', $sequential ) !== 1) {
            throw new InvalidArgumentException( sprintf( 'Sequential number should be between 1 and 9 (%s)',
                $sequential ) );
        }

        $this->sequential = intval( $sequential );

        return $this;
    }
@param  int $sequential

@return $this