title: Convert dict of nested lists to list of tuples
body: <p>I have <code>dict</code> of nested <code>list</code>s:</p>
  
  <pre><code>d = {'a': [[('a1', 1, 1), ('a2', 1, 2)]], 'b': [[('b1', 2, 1), ('b2', 2, 2)]]}
  print (d)
  {'b': [[('b1', 2, 1), ('b2', 2, 2)]], 'a': [[('a1', 1, 1), ('a2', 1, 2)]]}
  </code></pre>
  
  <p>I need create <code>list</code> of <code>tuple</code>s like:</p>
  
  <pre><code>[('b', 'b1', 2, 1), ('b', 'b2', 2, 2), ('a', 'a1', 1, 1), ('a', 'a2', 1, 2)]
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>a = [[(k, *y) for y in v[0]] for k,v in d.items()]
  a = [item for sublist in a for item in sublist]
  </code></pre>
  
  <p>I think my solution is a bit over-complicated. Is there some better, more pythonic, maybe one line solution?</p>