def __sort3(self, arr, l):
        """ Sort 2 or 3 arrays (very rubost and fast) """
        if l >= 2:
            if arr[0] > arr[1]: arr[0], arr[1] = arr[1], arr[0]
        if l == 3:
            if arr[1] > arr[2]: arr[1], arr[2] = arr[2], arr[1]
            if arr[0] > arr[1]: arr[0], arr[1] = arr[1], arr[0]
 Sort 2 or 3 arrays (very rubost and fast) 
recipes/Python/577898_23_Tree/recipe-577898.py