How do I fix an "'int' object is not iterable" error?

I’m working on the count problem, and have come up with the following code:

def count(sequence, item):
    found = 0
    for i in len(sequence):
        if sequence[i] == item:
           found = found + 1
    return found

but when I submit it I get an “‘int’ object is not iterable” error. I’m not really sure whether that means there’s a problem with the variable found which is an integer, or if sequence isn’t being recognised as a list…or some other possibility I haven’t thought of.

Can anyone explain what that error message means and how I should fix it?