title: Create a sublist from a list. First with second, second with third, etc
body: <p>From this</p>
  <pre><code>a = ['foo','bar','cat','dog']
  </code></pre>
  <p>to create another variable <code>b</code> that will have it as follows:</p>
  <pre><code>b = [['foo','bar'],['bar','cat'],['cat','dog']] # with this order
  </code></pre>
  <p>I have tried this:</p>
  <pre><code>b = [[i] * 2 for i in a]
  </code></pre>
  <p>but gives this:</p>
  <pre><code>[['foo', 'foo'], ['bar', 'bar'], ['cat', 'cat'], ['dog', 'dog']]
  </code></pre>
  <p>No external libraries please.</p>