in-place changes & non in-place changes

non in-place change:

for immutable object, such as number & string

ex:

a=3

b=a

b=2

--->  a=3 ,  b=2

in-place  changes:

for list , dictionary , etc

ex:

a=[1,2,3]

b=a

b[0]=5

--->  a=[5,2,3],  b=[5,2,3]

note:

a=[1,2]

b=a

b=[3,4]

--->  a is still [1,2]  because now  b & a point to different objects

the parameter of the function is passed by assignment 

Hence, it is the same.

If parameter is mutable, it can be changed

If parameter is not mutable, it can not be changed

how to change non-mutable argument for caller:

using return value

def  test(x, y)

     x=3

     y= 3

     return x, y

a=2

b=2

a, b= test(a, b)