def modify(self,x,y,z):
t=int(input("Enter the ISBN number of the book you want to issue:"))
with open(x,"rb") as f:
while(1):
try:
obj=pickle.load(f)
for i in obj:
if i.isbn == t:
p=int(input("Enter the number of copies:" ))
if(i.cp>=p):
i.cp=i.cp-p
b=Book()
b.Booki(z,y,p,t)
else:
print("Dont have enough copies!")
else:
print("Invalid ISBN There is no book")
except EOFError:
break
with open(x,"wb") as f:
pickle.dump(obj,f)
