input: Write a function to filter out all the even numbers from a given list and return the filtered list. If the given list is empty, return an empty list.
  assert filter_even_numbers([3, 4, 5, 6, 7])==[4, 6]
  assert filter_even_numbers([2, 4, 6, 8])==[2, 4, 6, 8]
  assert filter_even_numbers([1, 3, 5, 7])==[]
  assert filter_even_numbers([])==[]
output: def filter_even_numbers(lst):
      return [x for x in lst if x % 2 == 0]