def update(x):
     print(id(x))                               # here is giving a reference ids  

     x =8
     print(id(x))
     print("x",x)


a=10
print(id(a))
update(a)
print("a",a)




def update(lst):
    print(id(lst))
    lst[1]= 25
    print(id(lst))
    print("x",lst)

lst=[10,20,30]
print(id(lst))
update(lst)
print("lst",lst)