input: Write a python function to insert an item into a list at a specified position.
  assert insert_item(["Red", "Orange", "Yellow"], "Black", 2) == ["Red", "Orange", "Black", "Yellow"]
  assert insert_item([1, 2, 3, 4], 5, 2) == [1, 2, 5, 3, 4]
  assert insert_item(["a", "b", "d"], "c", 2) == ["a", "b", "c", "d"]
output: def insert_item(lst, item, position):
      lst.insert(position, item)
      return lst