co.js

import assert from 'assert';
import co from 'co';

const state1 = (_) => new Promise((resolve, reject) => {
  resolve(5);
});
const state2 = (a) => new Promise((resolve, reject) => {
  resolve(a + 5);
});
const state3 = (b) => new Promise((resolve, reject) => {
  resolve(b + 5);
});

const error = e => console.log(e.stack);

co(function *() {
  let _;
  let states = [state1, state2, state3];
  assert.equal(_ = yield states.shift()(_), 5);
  assert.equal(_ = yield states.shift()(_), 10);
  assert.equal(_ = yield states.shift()(_), 15);
}).catch(error);