format function is not working in python

Hi there! Would it be comforting to know that it's working just fine? It's actually doing the join with the string just as expected. The problem here is that you're not displaying the result of the operation. So if I edit your code just slightly, you can see the results.

flavor = ['chocolate','mint','strawberry']

print("My favourite flavour : {}".format(", ".join(flavor)))

Alternatively, you could store the results of your operation in a variable and print that out. This will be needed in an upcoming challenge by the way.

flavor = ['chocolate','mint','strawberry']

results = "My favourite flavour : {}".format(", ".join(flavor))
print(results)

Remember that computers are actually pretty dumb. They won't do anything you don't tell them to do. So if you never tell them to show the results of an operation... they won't.

Hope this helps!