title: Python swapping lists
body: <p>In python, when I assign a list to another, like:</p>
  
  <pre><code>a = [1,2,3]
  b = a
  </code></pre>
  
  <p>Now b and a point to the same list. Now considering two lists,</p>
  
  <pre><code>a = [1,2,3]
  b = [4,5,6]
  a,b = b,a
  </code></pre>
  
  <p>Now how is it that they are swapped like any other data type and does not end up both pointing to the same list?</p>