title: Add a new item to a dictionary in Python
body: <p>How do I add an item to an existing dictionary in Python? For example, given:</p>
  <pre><code>default_data = {
      'item1': 1,
      'item2': 2,
  }
  </code></pre>
  <p>I want to add a new item such that:</p>
  <pre><code>default_data = default_data + {'item3': 3}
  </code></pre>