title: Matrix class definition
body: <p>I need some help especially for b). Thank you</p>
  
  <p>Define a class for matrices as follows:
  (a) Provide an implementation of <code>__init__</code> that takes a list of lists as input
  and returns a new object of type matrix. </p>
  
  <p>For the matrix A =</p>
  
  <pre><code>1 2
  3 4
  </code></pre>
  
  <p>a user could enter <code>A = matrix( [[1,2],[3,4]])</code>.</p>
  
  <p>(b) Provide an implementation of <code>__repr__</code> that returns a string representation of a matrix, printing each row in a separate line, e.g. printing A
  as:</p>
  
  <pre><code>1, 2
  3, 4
  </code></pre>