def bubbleSort(a_list) :
    for pass_num in range(len(a_list)-1,0,-1) :
        for i in range(pass_num) :
            if a_list[i] > a_list[i+1] :
                temp = a_list[i]
                a_list[i] = a_list[i+1]
                a_list[i+1] = temp

if __name__ == '__main__':
    a_list = [54, 26, 93, 17, 77, 31, 44, 55, 20]
    bubbleSort(a_list)
    print(a_list)
