const Right = x => ({    chain    : f => f(x),    ap       : other => other.map(x),    traverse : (of, f) => f(x).map(Right),    map      : f => Right(f(x)),    fold     : (f, g) => g(x),    concat   : o => o.fold(_ => Right(x), y => Right(x.concat(y))),    toString : () => `Right(${x})`});const Left = x => ({    chain    : f => Left(x),    ap       : other => Left(x),    traverse : (of, f) => of(Left(x)),    map      : f => Left(x),    fold     : (f, g) => f(x),    concat   : o => o.fold(_ => Left(x), y => o),    toString : () => `Left(${x})`});const fromNullable = x => x != null ?                          Right(x) :                          Left(null);const Task = require(‘data.task‘);const {List} = require(‘immutable-ext‘);const fake = id =>    ({        id,        name: ‘user1‘,        best_friend_id: id + 1    });const Db = ({    find: id =>        new Task((rej, res) => {            res(id > 2 ? Right(fake(id)) : Left(‘not found‘))        })});const eitherToTask = e =>    e.fold(        Task.rejected,        Task.of    ); // Right(x) --> Task(user)const res = Db.find(3) // Task(Right(user))    .chain(eitherToTask) // Task(user)    .chain(user =>        Db.find(user.best_friend_id)    ) // Task(Right(user))    .chain(eitherToTask) // Task(user)    .fork(e => console.error(e),          r => console.log(r)    );