text: require('core-js/features/set')
  require('core-js/features/map')
  require('core-js/features/symbol')
  require('core-js/features/array')
  require('core-js/features/object')
  
  function addCustomEventPolyfill() {
    if (typeof window.CustomEvent === 'function') {
      // If not IE
      return false
    }
  
    function CustomEvent(
      event,
      params = { bubbles: false, cancelable: false, detail: undefined },
    ) {
      const { bubbles, cancelable, detail } = params
      const customEvent = document.createEvent('CustomEvent')
  
      customEvent.initCustomEvent(customEvent, bubbles, cancelable, detail)
  
      return customEvent
    }
  
    CustomEvent.prototype = window.Event.prototype
  
    window.CustomEvent = CustomEvent
  }
  
  function addArrayFlatPolyfill() {
    const ArrayPrototype = Array.prototype
  
    if ('flatten' in ArrayPrototype && !('flat' in ArrayPrototype)) {
      ArrayPrototype.flat = ArrayPrototype.flatten
    }
  }
  addCustomEventPolyfill()
  addArrayFlatPolyfill()
  