input: Write a function to return a set from an array.
  assert my_function([1, 2, 2, 3, 4, 4, 5]) == {1, 2, 3, 4, 5}
  assert my_function([10, 20, 20, 30, 40, 40, 50]) == {10, 20, 30, 40, 50}
  assert my_function([5, 7, 7, 9, 8, 6, 4, 3, 3]) == {3, 4, 5, 6, 7, 8, 9}
output: def my_function(arr):
      return set(arr)