How To Let People Know You're A Bad Python Programmer(artificialcode.blogspot.com)

  def name_printer(name):
      def printer():
          print(name)
      return printer

  erlanger_printer = name_printer('erlanger')

  >>> def foo():
  ...   blah = 42
  ...   def wibble():
  ...     print "blah is " + blah
  ...   wibble()
  ... 
  >>> foo()
  blah is 42

  >>> def foo():
  ...   blah = 42
  ...   def wibble():
  ...     blah += 1 
  ...   wibble()
  ...   print "blah is " + blah
  ... 
  >>> foo()
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "<stdin>", line 5, in foo
    File "<stdin>", line 4, in wibble
  UnboundLocalError: local variable 'blah' referenced before assignment