old_contents: const test = require('tape')
  const BorrowState = require('../lib/module.js')
  
  const sleep50ms = require('./sleep.js')
  
  ;[true, false].forEach((unsafe) => {
    test(`read-only-parallel (${unsafe ? 'un' : ''}safe)`, (t) => {
      t.plan(3)
      t.timeoutAfter(100)
      let myState = new BorrowState()
      ;[1, 2, 3].forEach(() => {
        myState.block('r')
          .then(sleep50ms)
          .then((state) => {
            t.ok(true)
            state.unblock()
          })
      })
    })
  })
  
new_contents: const test = require('tape')
  const BorrowState = require('../lib/module.js')
  
  const sleep50ms = require('./sleep.js')
  const countTo = require('./count-to.js')
  
  ;[true, false].forEach((unsafe) => {
    test(`read-only-parallel (${unsafe ? 'un' : ''}safe)`, (t) => {
      t.plan(3)
      t.timeoutAfter(100)
      let myState = new BorrowState()
      countTo(3).forEach(() => {
        myState.block('r')
          .then(sleep50ms)
          .then((state) => {
            t.ok(true)
            state.unblock()
          })
      })
    })
  })
  
subject: Use count-to in read-only-parallel