old_contents: def get_42():
      return 42
  
new_contents: def compare(path: str):
      """Compares given page content with other registered pages,
      and populates a duplication matrix.
  
      :param path: The path to a file containing what should be compared.
      """
      pass
  
  
  class Comparator:
      def __init__(self):
          self.matrix = {}
  
      def add_result(self, url1: str, url2: str, result: float):
          try:
              self.matrix[url2][url1] = result
          except KeyError:
              if self.matrix.get(url1):
                  self.matrix[url1][url2] = result
              else:
                  self.matrix[url1] = {url2: result}
  
      def exists(self, url1: str, url2: str):
          try:
              return self.matrix[url1][url2] is not None
          except KeyError:
              return False
  
subject: add class Comparator