input: 
  def count_even_numbers(numbers: List[int]) -> int:
      """ Count the number of even numbers in a given list of integers.
      >>> count_even_numbers([1, 2, 3, 4, 5])
      2
      >>> count_even_numbers([11, 22, 33, 44, 55])
      2
      """
  
output:     count = 0
      for num in numbers:
          if num % 2 == 0:
              count += 1
      return count