input: Write a function to implement the insertion sort algorithm for sorting n distinct integers in Python.
  def insertion_sort(arr):
      for i in range(1, len(arr)): 
          key = arr[i] 
          j = i-1
          while j >= 0 and key < arr[j] : 
                  arr[j + 1] = arr[j] 
                  j -= 1
          arr[j + 1] = key
  assert insertion_sort([3, 4, 5, 1, 2])==[1, 2, 3, 4, 5]
  assert insertion_sort([3, 5, 10, 1, 2])==[1, 2, 3, 5, 10]
  assert insertion_sort([4, 3, 1, 2])==[1, 2, 3, 4]
  assert insertion_sort([3, 5, 4, 1, 2])==[1, 2, 3, 4, 5]
  assert insertion_sort([])==[]
output: def insertion_sort(arr):
      for i in range(1, len(arr)): 
          key = arr[i] 
          j = i-1
          while j >= 0 and key < arr[j] : 
                  arr[j + 1] = arr[j] 
                  j -= 1
          arr[j + 1] = key