Bubblesort can be implemented in Python as

def bubble$\_$sort$($arr$)$:

for n in range$($len$($arr$)-1,0,-1)$:

for i in range$($n$)$:

if arr$[$i$]>$ arr$[$i $+1]$:

arr$[$i$],$ arr$[$i $+1]=$ arr$[$i $+1],$ arr$[$i$]$

Find a loop invariants for the inner and for the outer loop that help establishing its correctness.