title: reshape 2d list
body: <p>I'm trying to implement this function but I'm not sure exactly how to do so. I know we have to use a for loop for this problem but as with setting with variables and such, or if it contains a nested for loop, I am unsure. </p>
  
  <pre><code>def reshape(thelist, rows, cols):
      """Returns: A rows*cols 2D list with the contents of thelist
  
      Hint:  In a 2D list, the element at row x and col y is the
      x*cols+y element listed.
  
      Example: reshape([1,2,3,4],2,2) returns [[1,2], [3,4]]
      Example: reshape([1,2,3,4,5,6],3,2) returns [[1,2], [3,4], [5,6]]
      Example: reshape([1,2,3,4,5,6],2,3) returns [[1,2,3] ,[4,5,6]]
  
      Precondition: thelist is a list of numbers of size rows*cols. rows
      and cols are positive integers."""
  </code></pre>