Jupyter Notebook - Random Module Flip a coin

I'm very new to this website and I am a novice at Python, I've just started. This may have been asked many times now, but I'm not sure why the following code is not running:

import random

output={"Heads":0, "Tails":0}
coin=list(output.keys())

for a in range(10000):
    output[random.choice(coin)]+=1
    
print("Heads:", output["Heads"])
print("Tails:", output["Tails"])

Expected Result : It should randomly give you the total of how many times it was heads and tails whilst flipping the coin 10,000 times.

Actual Result: TypeError: 'list' object is not callable

I've googled this problem and it seems you have to use a square bracket but I'm not sure where to amend this. This code works for Python IDLE but not for Jupyter Notebook.

Any help would be much appreciated, thank you.

Peter.