The Python Apprentice

Implementing relocate_passenger()

Now we've laid the groundwork for our relocate_passenger() method:

class Flight:    # ...    def relocate_passenger(self, from_seat, to_seat):        """Relocate a passenger to a different seat.        Args:            from_seat: The existing seat designator for the                       passenger to be moved.            to_seat: The new seat designator.        """        from_row, from_letter = self._parse_seat(from_seat)        if self._seating[from_row][from_letter] is None:           raise ValueError(              "No passenger to relocate in seat {}".format(from_seat))        to_row, to_letter = self._parse_seat(to_seat)        if self._seating[to_row][to_letter] is not None:           raise ValueError(                "Seat {} already occupied".format(to_seat))        self._seating[to_row][to_letter] = self._seating[from_row]         [from_letter] self._seating[from_row][from_letter] ...