Reassigned the variable on python 3

>>> my_string="I am"

>>>print(my_string)

>>>my_string += " back"

>>>print(my_string)

Note: The empty space is required before back my_string value. otherwise, it considers as without space.

output:

I am

I am back

we assign a variable with another variable.please to follow the below steps 

>>>a=1

>>>b=a

>>>a=4

>>>print(a)

>>>print(b)

output:-

4

1