public function plus($number)
    {
        self::mustBeNumeric($number, 'Value to add');
        
        $number = is_object($number) ? $number->value : $number;

        return new self($this->value + $number);
    }
public function plus($number)
    {
        self::mustBeNumeric($number, 'Value to add');
        
        $number = is_object($number) ? $number->value : $number;

        return new self($this->value + $number);
    }
public function plus ( $ number ) { self :: mustBeNumeric ( $ number , 'Value to add' ) ; $ number = is_object ( $ number ) ? $ number -> value : $ number ; return new self ( $ this -> value + $ number ) ; }
Adds current number to given argument.

Create new `\Malenki\Bah\N` having the sum of given argument with
current number

@param  mixed $number Numeric-like value
@return N
@throws \InvalidArgumentException If argument is not N or numeric value.
Adds current number to given argument .