input: def insertion_sort(lst: List[int]) -> List[int]:
      """
      Implements the insertion sort algorithm that sorts a list of integers in ascending order.
      
      >>> insertion_sort([5, 2, 9, 1, 5, 6])
      [1, 2, 5, 5, 6, 9]
      >>> insertion_sort([3, 7, 4, 8, 2])
      [2, 3, 4, 7, 8]
      >>> insertion_sort([])
      []
      >>> insertion_sort([1])
      [1]
      """
  
      for i in range(1, len(lst)):
          key = lst[i]
          j = i - 1
          while j >= 0 and key < lst[j]:
              lst[j + 1] = lst[j]
              j -= 1
          lst[j + 1] = key
      return lst
output:     for i in range(1, len(lst)):
          key = lst[i]
          j = i - 1
          while j >= 0 and key < lst[j]:
              lst[j + 1] = lst[j]
              j -= 1
          lst[j + 1] = key
      return lst