class List {
    arr = [];

    constructor(add, remove, get, size) {


        this.add = function add(element) {
            this.arr.push(element)
        }

        this.remove = function remove(index) {
            if (this.arr.indexOf(index) !== -1) {
                throw new Error(`Index doesn't exist`);
            } else {
                this.arr.splice(index, 1);
            }
        }

        this.get = function get(index) {
            if (this.arr.indexOf(index) !== -1) {
                throw new Error(`Index doesn't exist`);
            } else {
                return this.arr[index];
            }
        }
        this.size = function size() {
            return this.arr.length;
        }
    }
}