input: Write a function to iterate over a list of numbers and print only the even numbers. The function should take a list of integers as an input parameter.
  assert print_even_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
  assert print_even_numbers([-2, 0, 2, 4, 6, 8])
  assert print_even_numbers([1, 3, 5, 7, 9])
  assert print_even_numbers([-4, -3, -2, -1, 0, 1, 2, 3, 4])
  assert print_even_numbers([])
output: def print_even_numbers(numbers):
      for num in numbers:
          if num % 2 == 0:
              print(num)