old_contents: class OverflowDate(object):
      def __init__(self, **info):
          self.info = info
  
      def isocalendar(self):
          if 'isocalendar' in self.info:
              return self.info['isocalendar']
          return None
  
  
new_contents: class OverflowDate(object):
      def __init__(self, **info):
          self.info = info
  
      def isocalendar(self):
          if 'isocalendar' in self.info:
              return self.info['isocalendar']
  
  
subject: Remove this line - it is redundant and missing code coverage.