Read the section on IntEnums[1]:

  IntEnum values behave like integers in other ways
  you'd expect:

  >>> int(Shape.circle)
  1
  >>> ['a', 'b', 'c'][Shape.circle]
  'b'
  >>> [i for i in range(Shape.square)]
  [0, 1]

[1] http://www.python.org/dev/peps/pep-0435/#intenum