create(digCallback) {
        let left = this._x1 - 1;
        let right = this._x2 + 1;
        let top = this._y1 - 1;
        let bottom = this._y2 + 1;
        let value = 0;
        for (let x = left; x <= right; x++) {
            for (let y = top; y <= bottom; y++) {
                if (x + "," + y in this._doors) {
                    value = 2;
                }
                else if (x == left || x == right || y == top || y == bottom) {
                    value = 1;
                }
                else {
                    value = 0;
                }
                digCallback(x, y, value);
            }
        }
    }
@param {function} digCallback Dig callback with a signature (x, y, value). Values: 0 = empty, 1 = wall, 2 = door. Multiple doors are allowed.