input: Write a python function to get all negative numbers from a list.
  assert get_negative_numbers([1, -2, 3, -4, 5, -6, 7, -8, 9, -10]) == [-2, -4, -6, -8, -10]
  assert get_negative_numbers([-1, -2, -3, -4, -5]) == [-1, -2, -3, -4, -5]
  assert get_negative_numbers([1, 2, 3, 4, 5]) == []
output: def get_negative_numbers(lst):
      return [num for num in lst if num < 0]