input: Write a function to filter out all the even numbers from a given list. Return a new list containing only the even numbers.
  assert filter_even_numbers([3, 4, 5, 6, 7])==[4, 6]
  assert filter_even_numbers([1, 2, 3, 4, 5])==[2, 4]
  assert filter_even_numbers([10, 11, 12, 13, 14])==[10, 12, 14]
  assert filter_even_numbers([])==[]
output: def filter_even_numbers(lst):
      return [x for x in lst if x % 2 == 0]