input: Write a function to filter a list of integers and return only the even numbers.
  
  assert filter_even_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == [2, 4, 6, 8, 10]
  assert filter_even_numbers([11, 13, 15, 17, 19]) == []
  assert filter_even_numbers([12, 14, 16, 18, 20]) == [12, 14, 16, 18, 20]
  assert filter_even_numbers([]) == []
  assert filter_even_numbers([0]) == [0]
output: def filter_even_numbers(numbers):
      return [num for num in numbers if num % 2 == 0]