text: import Ember from 'ember';
  
  const {get, set, computed, observer} = Ember;
  
  export default Ember.Helper.extend({
    content: computed('needle', 'haystack.[]', function() {
      let needle = get(this, 'needle');
      let haystack = get(this, 'haystack');
      return haystack.includes(needle);
    }).readOnly(),
  
    compute([haystack, needle]) {
      set(this, 'needle', needle);
      set(this, 'haystack', haystack);
      return get(this, 'content');
    },
  
    contentDidChange: observer('content', function() {
      this.recompute();
    })
  });
  