          # ...
  
      def _park_starting_at_spot(self, spot, vehicle):
          """Occupy starting at spot.spot_number to vehicle.spot_size."""
          # ...
  
  
  class ParkingSpot(object):
  
      def __init__(self, level, row, spot_number, spot_size, vehicle_size):
 
</s> remove         # ...
 </s> add         pass </s> remove     def park_vehicle(self, vehicle):  # ...
    def remove_vehicle(self):  # ... </s> add  </s> remove     def move_to_front(self, node):  # ...
    def append_to_front(self, node):  # ...
    def remove_from_tail(self):  # ...
 </s> add     def move_to_front(self, node):
        pass

    def append_to_front(self, node):
        pass

    def remove_from_tail(self):
        pass </s> remove     def message_user(self, friend_id, message):  # ...
    def message_group(self, group_id, message):  # ...
    def send_friend_request(self, friend_id):  # ...
    def receive_friend_request(self, friend_id):  # ...
    def approve_friend_request(self, friend_id):  # ...
    def reject_friend_request(self, friend_id):  # ...
 </s> add     def message_user(self, friend_id, message):
        pass

    def message_group(self, group_id, message):
        pass

    def send_friend_request(self, friend_id):
        pass

    def receive_friend_request(self, friend_id):
        pass

    def approve_friend_request(self, friend_id):
        pass

    def reject_friend_request(self, friend_id):
        pass </s> remove     def notify_call_escalated(self, call):  # ...
    def notify_call_completed(self, call):  # ...
    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):  # ... </s> add 
        pass
          # ...
  
      def _park_starting_at_spot(self, spot, vehicle):
          """Occupy starting at spot.spot_number to vehicle.spot_size."""
        pass
  
  
  class ParkingSpot(object):
  
      def __init__(self, level, row, spot_number, spot_size, vehicle_size):
keep keep keep keep replace keep keep keep keep keep
 Convert all .py files to be valid Python (#98) 
solutions/object_oriented_design/parking_lot/parking_lot.py