Function with_assigned_ipv4_addr_subnets 

pub fn with_assigned_ipv4_addr_subnets<BT: IpDeviceStateBindingsTypes, CC: IpDeviceStateContext<Ipv4, BT>, O, F: FnOnce(Box<dyn Iterator<Item = AddrSubnet<Ipv4Addr, Ipv4DeviceAddr>> + '_>) -> O>(
    core_ctx: &mut CC,
    device_id: &CC::DeviceId,
    cb: F,
) -> O

Calls the callback with an iterator of the IPv4 addresses assigned to device_id.