Count expensive items
Write count_over(prices, limit) that returns how many values in prices
are strictly greater than limit.
count_over([40, 25, 60, 2.5], 30) -> 2
count_over([40, 25, 60, 2.5], 60) -> 0
def count_over(prices, limit):
count = 0
for price in prices:
...
return count