text: const createMockRaf = require('mock-raf')
  export let mock = {_: createMockRaf()}
  export let cancel = (...args) => mock._.cancel(...args)
  export let step = (...args) => mock._.step(...args)
  export const reset = () => {
    mock._ = createMockRaf()
  }
  export default cb => mock._.raf(cb)
  