title: Sort a list within the key domain
body: <p>I have a list that looks like this: <code>my_list = [('a', 4), ('z', 3), ('y', 3), ('x', 3), ('p', 2), ('o', 2)]</code>.</p>
  <p>It is important that the tuples in the list are sorted by the second element ([1]) in the descending order.</p>
  <p>Now I need to sort each group of tuples with the same second element in the ascending order based on the first element ([0]) within each group. In other words, I need to get the list</p>
  <p><code>my_new_list= [('a', 4), ('x', 3), ('y', 3), ('z', 3), ('o', 2), ('p', 2)]</code>.</p>
  <p>How can I write the sorted function with the proper lambda? I can't write just <code>my_list.sort(key=lambda item: item[0])</code> because it will break the descending order of the tuples  when they are sorted by their second elements.</p>
  <p>What should my lambda look like?</p>