title: Python KeyError when converting list of list to dictionary
body: <p>I'm stuck with this simple task. I have a list of lists and I need to convert it to a dictionary but so far without any success.</p>
  
  <p>I tried it with the code below, but it gives me KeyError:0</p>
  
  <pre><code>list = [[3,0,7,4,5],[2,3,0,1,2],[6,6,7,6,6]]
  
  d = {}
  for x in list:
      i = 0
      for number in x:
          d[i].append(number)
          i += 1
  </code></pre>
  
  <p>I need it to be like this:</p>
  
  <pre><code>{0: [3,2,6], 1: [0,3,6], 2: [7,0,7], 3: [4,1,6], 4: [5,2,6]}
  </code></pre>
  
  <p>Any help is appreciated, thanks in advance!</p>