title: List within dictionary to a list to represent nodes and edges
body: <p>I have this input:</p>
  
  <pre><code>data = {'A': [('B', 7), ('D', 5)], 
      'B': [('C', 8), ('D', 9), ('E', 7)],
      'C': [('E', 5)], 'D': [('E', 15), ('F', 6)]
      'E':[('F', 8), ('G', 9)], 
      'F':[('G', 11)]
  }
  </code></pre>
  
  <p>And I´m trying to convert it to:</p>
  
  <pre><code>[ ("A", "B", 7), ("A", "D", 5),
    ("B", "C", 8), ("B", "D", 9), ("B", "E", 7),
    ("C", "E", 5),
    ("D", "E", 15), ("D", "F", 6),
    ("E", "F", 8), ("E", "G", 9),
    ("F", "G", 11)]
  </code></pre>
  
  <p>I can't seem to make it work in this exact manner.</p>
  
  <p>Thanks.</p>