input: Write a function to filter even numbers from a list.
  assert filter_evennumbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == [2, 4, 6, 8, 10]
  assert filter_evennumbers([10, 21, 32, 45, 56, 67, 78, 89]) == [10, 32, 56, 78]
  assert filter_evennumbers([15, 22, 39, 40, 52, 63]) == [22, 40, 52]
output: def filter_evennumbers(lst):
      return [num for num in lst if num % 2 == 0]