Python - Why doesn't this add class attributes?

Question

Result should be 12:

class J(str):
def __init__(self,j):
self.j=j
'''
def __add__(self,other):
self.j+other.j
'''
def __add__(first,second):
first.j+second.j
x = J(5)
y = J(7)
print(x+y)

Answer 1

def __add__(self, other):
return self.j + other.j