1{den, ...}: {
 2  den.default.includes = [den.aspects.core._.time-sync];
 3  den.aspects.core.provides.time-sync = {host, ...}: {
 4    nixos = {
 5      # Use an NTP server located in the mainland of China to synchronize the system time
 6      networking.timeServers = [
 7        "ntp.aliyun.com" # Aliyun NTP Server
 8        "ntp.tencent.com" # Tencent NTP Server
 9      ];
10      services = {
11        timesyncd.enable = host.usage != "laptop";
12        chrony.enable = host.usage == "laptop";
13      };
14    };
15  };
16}