public function write($x, $y, $color)
    {
        if(isset($this->canvas[$y][$x])) {
            $this->canvas[$y][$x] = $color;
        }
    }
public function write($x, $y, $color)
    {
        if(isset($this->canvas[$y][$x])) {
            $this->canvas[$y][$x] = $color;
        }
    }
public function write ( $ x , $ y , $ color ) { if ( isset ( $ this -> canvas [ $ y ] [ $ x ] ) ) { $ this -> canvas [ $ y ] [ $ x ] = $ color ; } }
Scribble onto the stall

@param  int  $x
@param  int  $y
@param  int  $color
@return void
Scribble onto the stall