title: Adding each element in a 2d list to another 2d list in Python
body: <p>So i need to define a function, in which i get 2 lists that are 2d. The goal is to add each element to each other.</p>
  <pre><code>
  list1 = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
  list2 = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
  </code></pre>
  <p>the result should be this:</p>
  <pre><code>   result = [[2,4,6], [8,10,12],[14,16,18]]
  </code></pre>
  <p>So far, i built this function:</p>
  <pre><code>def add_matrices(list1, list2):
      matrix = list1 + list2
      return matrix
  </code></pre>
  <p>But im kinda stuck now, I have tried to use append and extend, but both didn't work. I have found a few solutions that required the usage of numpy, which unfortunately isn't allowed for this. Can anybody please guide me in the right direction?</p>