input: Write a python function to remove None values from a list.
  assert remove_none([1, None, 2, None, 3, 4, None, 5]) == [1, 2, 3, 4, 5]
  assert remove_none([None, None, None]) == []
  assert remove_none([7, 8, 9, None, 10]) == [7, 8, 9, 10]
output: def remove_none(lst):
      return [x for x in lst if x is not None]