old_contents: class Allergies(object):
  
      def __init__(self, number):
          pass
  
      def is_allergic_to(self, string):
          pass
  
      @property
      def lst(self):
          pass
  
new_contents: class Allergies(object):
  
      ALLERGENS = {1:"eggs", 2:"peanuts", 3:"shellfish", 4:"strawberries",
                   5:"tomatoes", 6:"chocolate", 7:"pollen", 8:"cats"}
  
      def __init__(self, number):
          self.number = number
  
      def is_allergic_to(self, string):
          return string in self.lst
  
      @property
      def lst(self):
          return [Allergies.ALLERGENS[k+1] for k in range(8)
                  if self.number & (1 << k)]
  
subject: Add initial solution