Fix #13, PEP8-ify notebooks.

stacks_queues/set_of_stacks/test_set_of_stacks.py

@@ -2,7 +2,7 @@ from nose.tools import assert_equal
 
 
 class TestSetOfStacks(object):
-    
+
     def test_set_of_stacks(self):
         print('Test: Push on an empty stack')
         capacity = 2
@@ -24,12 +24,14 @@ class TestSetOfStacks(object):
 
         print('Test: Pop on no elements')
         assert_equal(stacks.pop(), None)
-        
+
         print('Success: test_set_of_stacks')
 
+
 def main():
     test = TestSetOfStacks()
     test.test_set_of_stacks()
-    
+
+
 if __name__ == '__main__':
     main()