A notebook that stops on Run all

Yesterday this notebook worked because you ran the cells one at a time, in an order you chose. Today you opened it again and used "Run all" to run the cells in order from the top, and it stopped with an error in cell 2. The code below joins the cells of the notebook from the top. Lines that start with # are notes that say which cell each part is. Move just one cell so that running from the top prints Subscribers and then 350. Grading runs the code again with a different number of subscribers.

Code to fix

# Cell 1
print("Subscribers")
# Cell 2
print(subscribers)
# Cell 3
subscribers = 350