Enum in python

• Before Python 3.4 (PEP 435),

  class Animal:
      DOG = 1
      CAT = 2
  
  x = Animal.DOG
  

  or

  class Animal:
      DOG, CAT = range(2)
  
  x = Animal.DOG
  

• Since Python 3.4 (PEP 435),

  class Animal(Enum):
      DOG = 1
      CAT = 2
  
  x = Animal.DOG
  

  or equivalently:

  from enum import Enum
  
  Animal = Enum('Animal', 'DOG CAT')
  
  x = Animal.DOG