title: Getting rid of the second elemnt in a matrix of 2D tuples
body: <p>I would like to know how can I turn this matrix:                       </p>
  
  <pre><code> [[(2,1)][(3,1)][(3,2)]
    [(2,3)][(3,1)]][(11,3)]]
  </code></pre>
  
  <p>into:</p>
  
  <pre><code>[(2)][3)][3)]
    [2][3]][11]]
  </code></pre>
  
  <p>that is, earising the second elements of the tuples that construct my matrix (thus making it a regular matrix of scalars). I would like to know how to do the opposite of this - taking a regular matrix and turn it into a matrix of lists or tuples.</p>