rx with mfjs for do notation

rxmj.js

import {Observable} from 'rx'
const M = require('@mfjs/core')
const MM = require('@mfjs/rx')()
M.profile('regenerator')
const { just: pure, fromPromise,from } = Observable

let cnt = 0

function updateDb() {
  return new Promise(resolve => {
    setTimeout(
      () => {
        console.log(`DB UPDATED ${cnt}`)
        resolve(cnt++)
      }, 0)
  })
}
MM.run(function* () {
  const m = yield fromPromise(updateDb())
  const x = yield from([1,2])
  return `${x} ${m}`
}).subscribe(function(res) {
  console.log(res)
})
/*
outputs:
```
DB UPDATED 0
1 0
2 0
```
*/

let i = 0;
MM.run(function*() {
  const x = yield from([1,2])
  if (i++) {
    const y = yield from(['in then'])
    return `then ${x} ${y}` 
  } else {
    const y = yield from(['in else'])
    return `else ${x} ${y}` 
  }
}).subscribe(function(res) {
  console.log(res)
})
/*
outputs:
```
else 1 in else
then 2 in then
```
*/