कॉलम और पंक्तियाँ हटाना

# Remove the 'flight' column
flights_drop_column = flights.____(____)

# Number of records with missing 'delay' values
flights_drop_column.____('delay IS NULL').____()

# Remove records with missing 'delay' values
flights_valid_delay = flights_drop_column.____(____)

# Remove records with missing values in any column and get the number of remaining rows
flights_none_missing = flights_valid_delay.____()
print(flights_none_missing.____())