title: How two rows can be swapped in a torch tensor?
body: <pre><code>var = [[0, 1, -4, 8],
         [2, -3, 2, 1],
         [5, -8, 7, 1]]
  
  var = torch.Tensor(var)
  </code></pre>
  
  <p>Here, <code>var</code> is a 3 x 4 (2d) tensor. How the first and second row can be swapped to get the following 2d tensor?</p>
  
  <pre><code>2, -3, 2, 1 
  0, 1, -4, 8
  5, -8, 7, 1
  </code></pre>