Python Hata Alıyorum (Yardım Lazım)

#calculator project
#class -> init -> method/attribute -> funct vs method

class Clac(object):
#init metedu
def __init__(self,a,b):
"initialalize values"
#attribute
self.value1=a
self.value2=b
pass

def add(self):
"addition a+b = result -> retur result"
return self.value1 + self.value2

def multiply(self):
"multiplication a*b = result -> return result"
return self.value1 * self.value2



print("Choose add(1) , multiply(2)")
selection = input("select 1 or 2\n")

v1 = int(input("First value = "))
v2 = int(input("Second value = "))

c1 = Clac(v1,v2)


if selection == "1":
add_result = c1.add()
print("Add: {}".format(add_result))
elif selection == "2":
multiply_result = c1.multiply()
print("Multiply: {}".format( multiply_result))