old_contents: from skylines.model.geo import Location
  
  
  class Waypoint(Location):
      def __init__(self):
          self.altitude = 0
          self.name = ''
          self.short_name = ''
          self.icao = ''
          self.country_code = ''
          self.surface = None
          self.runway_len = None
          self.runway_dir = None
          self.freq = None
          self.type = None
  
      def __str__(self):
          return '{}, {}, {}, {}'.format(self.name,
                                         super(Waypoint, self).__str__(),
                                         self.altitude,
                                         self.type)
  
new_contents: from skylines.model.geo import Location
  
  
  class Waypoint(Location):
      def __init__(self):
          super(Waypoint, self).__init__()
  
          self.altitude = 0
          self.name = ''
          self.short_name = ''
          self.icao = ''
          self.country_code = ''
          self.surface = None
          self.runway_len = None
          self.runway_dir = None
          self.freq = None
          self.type = None
  
      def __str__(self):
          return '{}, {}, {}, {}'.format(self.name,
                                         super(Waypoint, self).__str__(),
                                         self.altitude,
                                         self.type)
  
subject: Add missing super().__init__() call