title: Check if the lengths inside a nested list are identical
body: <p>I have a list of lists and I want to calculate first the size of each sub-list and then to see whether all those sub-lists have size 2. Therefore,</p>
  
  <pre><code>my_list = [["obj1", "item1"], ["obj2", "item2", "item1"], ["obj3", "item3"], ["obj4", "item4"], ["obj5", "item5"]]
  lengths = [len(x) for x in my_list]
  </code></pre>
  
  <p>The list <code>lengths</code> contains the size of each sub-list. How can I check whether all my sub-lists have size two or not? In my example it should fail.</p>