title: React immutability helper - set new value at index in array
body: <p>Is there any way I can set value of array in specific index with React imutability helper ? </p>
  
  <p>For example something like this:</p>
  
  <pre><code>   const newState = update(this.state , {
          open[8]:{$set: false}
      })
      this.setState(newState);
  </code></pre>
  
  <p>or do I have to deep clone that array using JSON and then set new value at specific index and then use react imutability helper to update state?</p>