Verified answer

def rate_f(movies):

   if len(dictionary[movies]) == 0:

       return True

def film_in_dictionary(movies):

   if movies in dictionary:

       return True

   else:

       return False

def average(movies):

   mean = 0

   for key2 in dictionary[movies].keys():

       mean += dictionary[movies][key2]

   print(f'{movies} средняя оценка: {mean / len(dictionary[movies])}')

dictionary = {}

while True:

   command = input('Введите команду: ')

   if command != 'exit' and command != 'list' and command != 'add' and command != \

           'delete' and command != 'rate' and command != 'find':

       print('Error')

       continue

   if command == 'exit':

       break

   if command == 'list':

       for key in dictionary.keys():

           if rate_f(key):

               print(f'{key} не оценивался')

           else:

               average(key)

       continue

   film = input('Введите название фильма: ')

   if command == 'add':

       if film_in_dictionary(film):

           print('Error')

       else:

           dictionary[film] = {}

   elif command == 'delete':

       if film in dictionary:

           del dictionary[film]

       else:

           print('Error')

   elif command == 'rate':

       name = input('Имя пользователя: ')

       rate = float(input('Оценка: '))

       if 0 < rate <= 10:

           dictionary[film][name] = rate

       else:

           print('Error')

   elif command == 'find':

       if rate_f(film):

           continue

       for name, rate in dictionary[film].items():

           print(f'{name} поставил оценку: {rate}')

       average(film)