title: How to add new item to hash
body: <p>I'm new to Ruby and don't know how to add new item to already existing hash. For example, first I construct hash:</p>
  
  <pre><code>hash = {item1: 1}
  </code></pre>
  
  <p>after that a want to add item2 so after this I have hash like this:</p>
  
  <pre><code>{item1: 1, item2: 2}
  </code></pre>
  
  <p>I don't know what method to do on hash, could someone help me?</p>