input: Write a function to identify the number of even numbers present in a given list of numbers. If the list is empty, return 0.
  assert countEvenNum([1, 2, 3, 4, 5])==2
  assert countEvenNum([2, 4, 6, 8])==4
  assert countEvenNum([1, 3, 5, 7])==0
  assert countEvenNum([0, 1, 2, 0])==3
  assert countEvenNum([])==0
output: def countEvenNum(nums):
      return sum(1 for num in nums if num % 2 == 0)