title: Dynamic global variables assignment
body: <p>I'm new in python and I'm having many troubles in using <code>global</code> instruction.<br />
  Here is a code example:</p>
  
  <pre><code>mouse = "a"
  background = "b"
  
  list_ab = [mouse, background]
  
  def func ():
      for item in list_ab:
          global item  # I want to modify the GLOBAL item, which is mouse
                       # and background.
          item = "modified"
      print mouse  # must be "modified" not "a"
      print background  # must be "modified" not "b"
  </code></pre>
  
  <p>This is the problem. How can I solve it?</p>