text: function Array2d(width=0, height=0)
  {
      this.width = width;
      this.height = height;
      this.data = [];
  
      this.clear = function()
      {
          this.data = [];
          for (let y = 0; y < height; y++)
          {
              let row = [];
              for (let x = 0; x < width; x++)
              {
                  row.push(null);
              }
              this.data.push(row);
          }
      };
  
      this.get = function(x,y)
      {
          return this.data[y][x];
      };
  
      this.set = function(x,y,v)
      {
          this.data[y][x] = v;
          return this.data[y][x];
      };
  
      this.clear();
  }