title: How to group items in array?
body: <p>I have an array of items(day in month numbers), now I want to group them by month, so I want to turn this:</p>
  
  <pre><code>(1, True), ... (31, True), (1, False) ...(28, True),...
  </code></pre>
  
  <p>Into this:</p>
  
  <pre><code>[(1, True), ... (31, True)], [(1, False) ...(28, True)],...
  </code></pre>
  
  <p>I am using python 3. How should I do it?</p>