private function color(string $color): Font
    {
        $this->color = $color;

        if ($this->background) {
            $this->turnToBackground();
        }

        return $this;
    }
private function color(string $color): Font
    {
        $this->color = $color;

        if ($this->background) {
            $this->turnToBackground();
        }

        return $this;
    }
private function color ( string $ color ) : Font { $ this -> color = $ color ; if ( $ this -> background ) { $ this -> turnToBackground ( ) ; } return $ this ; }
function to set color to a string
@param string $color
@return Font
function to set color to a string