input: Write a function to count the number of elements greater than a given threshold.
  assert count_greater_than_threshold([1, 2, 3, 4, 5], 3) == 2
  assert count_greater_than_threshold([10, 20, 30, 40, 50], 25) == 3
  assert count_greater_than_threshold([5, 7, 9, 8, 6, 4, 3], 5) == 4
output: def count_greater_than_threshold(lst, threshold):
      return sum(1 for x in lst if x > threshold)