input: Write a python function to find all even numbers from a list of odd numbers.
  assert find_even_numbers([1, 3, 5, 7, 9, 11, 13, 15, 17, 19])==[]
  assert find_even_numbers([2, 4, 6, 8, 10, 12, 14, 16, 18, 20])==[2, 4, 6, 8, 10, 12, 14, 16, 18, 20]
  assert find_even_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])==[2, 4, 6, 8, 10]
output: def find_even_numbers(lst):
      return [num for num in lst if num % 2 == 0]