input: Write a python function to insert an element into a list at a given index.
  assert insert_element([1, 2, 3, 4], 2, 9) == [1, 2, 3, 9, 4]
  assert insert_element(['a', 'b', 'c'], 1, 'z') == ['a', 'b', 'z', 'c']
  assert insert_element([10, 20, 30], 0, 5) == [10, 5, 20, 30]
output: def insert_element(lst, index, element):
      lst.insert(index, element)
      return lst