input: Write a python function to merge two lists and remove duplicates.
  assert remove_duplicates([11, 7, 10, 2, 4], [10, 5, 8, 11]) == [11, 7, 10, 2, 4, 5, 8]
  assert remove_duplicates([1, 2, 3], [3, 4, 5]) == [1, 2, 3, 4, 5]
  assert remove_duplicates([10, 20, 30], [40, 50, 60]) == [10, 20, 30, 40, 50, 60]
output: def remove_duplicates(list1, list2):
      merged_list = list1 + list2
      return list(dict.fromkeys(merged_list))