def bubbleSort(alist):
     for passnum in range(len(alist)-1,0,-1):
         for i in range(passnum):
             if alist[i]>alist[i+1]:
                 temp = alist[i]
                 alist[i] = alist[i+1]
                 alist[i+1] = temp
 ​
 alist = [54,26,93,17,77,31,44,55,20]
 bubbleSort(alist)
 print(alist)
 ​