Surgical monitoring different network devices via SNMP

Exporters and Metrics
1

Hello,
I’m pretty new to Prometheus.
I have some Juniper EX switches and I would like to monitor the throughput of few interfaces. I would like to be more surgical possible.
I got the SNMP index of those interfaces which are different on each device.
I cannot understand how snmp-exporter works.
Should I write a module piece of configuration for each device specifying only the OID I would like to poll?

I mean something like:

modules:
   switch1
     walk:
       - 1.3.6.1.4.1.2636.3.3.1.1.1.919 
       - 1.3.6.1.4.1.2636.3.3.1.1.4.919
   switch2
     walk:
       - 1.3.6.1.4.1.2636.3.3.1.1.1.737 
       - 1.3.6.1.4.1.2636.3.3.1.1.4.737
....

Thanks