input: Write a python function to count numbers greater than 5 in a list.
  assert count_greater_than_five([1,2,3,4,5,6,7,8,9]) == 4
  assert count_greater_than_five([10, 20, 5, 3, 7]) == 3
  assert count_greater_than_five([1, 2, 3, 4, 5]) == 0
output: def count_greater_than_five(lst):
      return sum(1 for x in lst if x > 5)