human
Solve the following python programming problem given the following code:
def _validate_cidr(self, context, nets, subnets_v4, fixed_net_v4) : 
    used_subnets = [net.cidr for net in nets] 
    def find_next(subnet) : 
        next_subnet = subnet.next () 
        while (next_subnet in subnets_v4) : 
            next_subnet = next_subnet.next () 
if (next_subnet in fixed_net_v4) : 
            return next_subnet 
for subnet in list (subnets_v4) : 
        if (subnet in used_subnets) : 
            next_subnet = find_next (subnet) 
            if next_subnet : 
                subnets_v4.remove (subnet) 
                subnets_v4.append (next_subnet) 
                subnet = next_subnet 
else : 
                raise exception.CidrConflict (cidr = subnet, other = subnet) 
for used_subnet in used_subnets : 
            if (subnet in used_subnet) : 
                raise exception.CidrConflict (cidr = subnet, other = used_subnet) 
if (used_subnet in subnet) : 
                next_subnet = find_next (subnet) 
                if next_subnet : 
                    subnets_v4.remove (subnet) 
                    subnets_v4.append (next_subnet) 
                    subnet = nets 
else : 
                    raise exception.CidrConflict (cidr = subnet, other = used_subnet) 

    
    

    Fix the buggy line: subnet = nets
assistant
#Here is Python program to fix the buggy line: subnet = nets
.

subnet = next_subnet