input: 
  def insertion_sort(list):
      """Implement an insertion sort algorithm in Python.
      >>> insertion_sort([5, 3, 4, 1, 2])
      [1, 2, 3, 4, 5]
      >>> insertion_sort([7, 6, 8, 9, 10])
      [6, 7, 8, 9, 10]
      """
      for i in range(1, len(list)):
          key = list[i]
          j = i - 1
          while j >= 0 and key < list[j]:
              list[j + 1] = list[j]
              j -= 1
          list[j + 1] = key
      return list
  
output:     for i in range(1, len(list)):
          key = list[i]
          j = i - 1
          while j >= 0 and key < list[j]:
              list[j + 1] = list[j]
              j -= 1
          list[j + 1] = key
      return list