title: set operation on a list of elements
body: <p>I have a list containing thousands of sets similar to this: </p>
  
  <pre><code>set_list = [a, b, c, d]
  </code></pre>
  
  <p>each set in the list look something like this: </p>
  
  <pre><code>a = set([1, 2, 3, 4, 5])
  b = set([4, 5, 6, 7, 7, 9])
  c = set([1, 2, 6, 8, 10, 12, 45])
  d = set([11, 3, 23, 3, 4, 44])
  </code></pre>
  
  <p>I would like to do the set operation: X-(YUZUAUB......etc) for every set in the list, for example, this would look something like this: 
  after applying this operation on all elements in <code>set_list</code> the new elements look like this: </p>
  
  <pre><code>a = a.difference(b.union(c, d))
  b = b.difference(c.union(a, d))
  c = c.difference(d.union(b, a))
  d = d.difference(a.union(c, b))
  </code></pre>
  
  <p>how do i accomplish this?</p>