It’s ok to ask if you have a problem.
All the sub checks are normally inside one file.
In your example this file hast the name “smart” and includes two sub checks. But this is an agent based check. If you plan to do such a check with SNMP i would recommend the “cmciii” check as example.
This is also a very complex check 
It has a check without sub check - “cmciii” and then many “cmciii…”