title: Get mean squared error between every element in two tensors
body: <p>I have two single dimensional tensors, <code>y_pred</code> and <code>y_true</code>
  where:</p>
  <pre><code>&gt;&gt;&gt; y_pred.shape
  torch.Size([2730441, 1])
  &gt;&gt;&gt; y_true.shape
  torch.Size([2730441, 1])
  </code></pre>
  <p>To get the Mean Squared Error between the two tensors I can use
  <code>torch.nn.MSELoss()</code> However, I want to get the loss between each row/ element in the tensors <code>y_pred</code> &amp; <code>y_true</code> i.e. I want to run some function <code>elementWiseMSE(y_pred, y_true)</code> which will return <code>loss_tensor</code> of shape <code>[2730441, 1]</code> which contains the elementwise mean error of all the predictions.</p>