title: How can I unroll a PyTorch Tensor?
body: <p>I have a tensor:</p>
  <pre><code>t1 = torch.randn(564, 400)
  </code></pre>
  <p>I want to unroll it to a 1-d tensor that's <code>225600</code> long.</p>
  <p>How can I do this?</p>