title: Indexing and slicing in numpy
body: <pre><code>x = np.array([[[1],[2],[3]], [[4],[5],[6]]])
  x.shape
  (2,3,1)
  x[1:3]
  array([[[4],
      [5],
      [6]]])
  </code></pre>
  
  <p>I am expecting error in  x[1:4] because index out bound but it gives output how it is possible.</p>