input: Write a python function to remove duplicate elements from a list.
  assert remove_duplicate([1, 2, 3, 4, 3, 2, 4]) == [1, 2, 3, 4]
  assert remove_duplicate([5, 5, 5, 5, 5]) == [5]
  assert remove_duplicate([1, 2, 3, 4, 5, 6, 7, 8, 9]) == [1, 2, 3, 4, 5, 6, 7, 8, 9]
  assert remove_duplicate([10, 20, 20, 30, 10, 40]) == [10, 20, 30, 40]
output: def remove_duplicate(lst):
      return list(dict.fromkeys(lst))