iterate(f) {
        this._s.forEach(n => {
            const y = n & 0xFFFF;
            const x = n >> 16;
            f(x, y);
        });
    }
/**
     * iterates through all markers and call a function back for each marked position
     * @param f {function}
     */
iterates through all markers and call a function back for each marked position
@param f {function}
iterates through all markers and call a function back for each marked position @param f { function }
iterate(f) {
        this._s.forEach(n => {
            const y = n & 0xFFFF;
            const x = n >> 16;
            f(x, y);
        });
    }
iterate ( f ) { this . _s . forEach ( n => { const y = n & 0xFFFF ; const x = n >> 16 ; f ( x , y ) ; } ) ; }
iterates through all markers and call a function back for each marked position
 @param f {function}
iterates through all markers and call a function back for each marked position @param f { function }