this.children = Array.from(wrapper.children)

this.children.forEach((child, i) => {
    let classes = child.classList;
    classes.toggle('flic-before', i < s+1);
    classes.toggle('flic-active', i === s);
    classes.toggle('flic-previous', i === s-1);
    classes.toggle('flic-next', i === s+1);
})