input: Write a python function to count how many numbers in a list are greater than a given user number.
  assert count_greater_than_user(5, [6, 7, 8, 9, 10]) == 5
  assert count_greater_than_user(8, [6, 7, 8, 9, 10]) == 2
  assert count_greater_than_user(10, [6, 7, 8, 9, 10]) == 0
output: def count_greater_than_user(user_number, numbers):
      count = 0
      for number in numbers:
          if number > user_number:
              count += 1
      return count