Unable to debug the syntax error and need some asisstance - python-3.6

Question

I am learing Python3.6 and spent a long time looking at this code to debug a syntax error occurring in the allcoate_seat function, position "if row not in rows:" and wanted to share this and find out the reason. I am still building the code and stuck at this position.
Code snippet:
class Flight:
def __init__(self, fnumber, aircraft):
if not fnumber[:2].isalpha():
raise ValueError ("No airline code in {}".format(fnumber))
if not fnumber[:2].isupper():
raise ValueError ("Invalid airline code in {}".format(fnumber))
if not (fnumber[2:].isdigit() and int(fnumber[2:]))<9999:
raise ValueError ("Invalid route in {}".format(fnumber))
self.fnumber=fnumber
self.aircraft=aircraft
rows, seats = aircraft.seating_plan()
self.seating=[None] + [{letter:None for letter in seats} for _ in rows]
def fnumber (self):
return self.fnumber
def airline(self):
return self.fnumber[:2]
def aircraft_model(self):
return self.aircraft.model()
def allcoate_seat(self, seat, passenger):
rows, seat_letters=self._aircraft.seating_plan()
letter=seat[-1]
if letter not in seat_letters:
raise ValueError ('Invalid seat letters {}'.format(letter))
row_text=seat[:-1]
try:
row=int(row_text)
except ValueError:
raise ValueError('Invalid seat row {}'.format(row_text)
if row not in rows:
raise ValueError ('Invalid row number {}'.format(row))
if self._seating[row][letter] is not None:
raise ValueError ('Seat already allocated {}'.format(seat))
self._seating[row][letter]=passenger
class Aircraft:
def __init__(self, registration, model, num_rows, num_seats_per_row):
self._registration=registration
self._model=model
self._num_rows=num_rows
self._num_seats_per_row=num_seats_per_row
def registration(self):
return self._registration
def model(self):
return self._model
def seating_plan(self):
return(range(1,self._num_rows+1),'ABCDEFGHJ'[:self._num_seats_per_row])
f1= Flight('TA098', Aircraft('TA008','AirbusA380',10,5))
print(f1.fnumber, f1.aircraft_model(), f1.airline(), pp(f1.seating))