title: Python: list is not mutated after for loop
body: <pre><code>a =[1,2]
  for entry in a:
      entry = entry + 1
  print a  
  </code></pre>
  
  <p>Shouldn't the list be mutated to<code>[2,3]</code>? The result came out as <code>[1,2]</code>.
  Why?</p>