input: Write a function that filters a list of integers and returns only even numbers. If the input list is empty, the function should return an empty list.
  
  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]) == []
  assert filter_even_numbers([2, 4, 6, 8, 10]) == [2, 4, 6, 8, 10]
  assert filter_even_numbers([1, 3, 5, 7, 9]) == []
  assert filter_even_numbers([]) == []
output: def filter_even_numbers(lst):
      return [x for x in lst if x % 2 == 0]