title: Python - tuple unpacking in dict comprehension
body: <p>I'm trying to write a function that turns strings of the form <code>'A=5, b=7'</code> into a dict <code>{'A': 5, 'b': 7}</code>. The following code snippets are what happen inside the main <code>for</code> loop - they turn a single part of the string into a single dict element.</p>
  
  <p>This is fine:</p>
  
  <pre><code>s = 'A=5'
  name, value = s.split('=')
  d = {name: int(value)}
  </code></pre>
  
  <p>This is not:</p>
  
  <pre><code>s = 'A=5'
  d = {name: int(value) for name, value in s.split('=')}
  ValueError: need more than 1 value to unpack
  </code></pre>
  
  <p>Why can't I unpack the tuple when it's in a dict comprehension? If I get this working then I can easily make the whole function into a single compact dict comprehension.</p>