old_contents: __all__ = ['isnone', 'notnone', 'inc', 'dec', 'even', 'odd']
  
  
  EMPTY = object() # Used as unique default for optional arguments
  
  
  def isnone(x):
      return x is None
  
  def notnone(x):
      return x is not None
  
  
  def inc(x):
      return x + 1
  
  def dec(x):
      return x - 1
  
  def even(x):
      return x % 2 == 0
  
  def odd(x):
      return x % 2 == 1
  
new_contents: __all__ = ['isnone', 'notnone', 'inc', 'dec', 'even', 'odd']
  
  
  class EmptyType:
      def __repr__(self):
          return 'EMPTY'
  
  EMPTY = EmptyType() # Used as unique default for optional arguments
  
  
  def isnone(x):
      return x is None
  
  def notnone(x):
      return x is not None
  
  
  def inc(x):
      return x + 1
  
  def dec(x):
      return x - 1
  
  def even(x):
      return x % 2 == 0
  
  def odd(x):
      return x % 2 == 1
  
subject: Make pretty EMPTY value