title: In python why is list[i:i] = [n] insert an element in list[i:i]
body: <p>Why do python have this behavior ? how can it be explained ?</p>
  
  <pre><code>mylist=[5, 9, 13, 15, 16]
  n=14
  i=0
  mylist[i:i] = [n]
  print(mylist)
  
  
  Output:
  [14, 5, 9, 13, 15, 16]
  </code></pre>