input: Write a python function that duplicates a list using a single-element tuple.
  assert duplicate_list([1, 2, 3]) == [1, 2, 3]
  assert duplicate_list([4, 8, 2, 10, 15, 18]) == [4, 8, 2, 10, 15, 18]
  assert duplicate_list([4, 5, 6]) == [4, 5, 6]
output: def duplicate_list(input_list):
      return [element for element in (input_list,)]