input: from typing import List
  
  def countEvenNum(numbers: List[int]) -> int:
      """ Count the number of even numbers in a given list of integers.
      >>> countEvenNum([1, 2, 3, 4, 5])
      2
      >>> countEvenNum([2, 4, 6, 8])
      4
      """
      return len([x for x in numbers if x % 2 == 0])
output:     return len([x for x in numbers if x % 2 == 0])