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):
  
      def __init__(self, score):
          pass
  
      def is_allergic_to(self, item):
          pass
  
      @property
      def lst(self):
          pass
  
subject: Update parameters in exercise placeholder; closes #539