Is there a bus that is the null equivalent?

I have a synthdef that has multiple bus inputs. Is it customary to have a bus that is designated to not be in use, so, when I create a synth but need only one bus input, the other is set to the not in use bus? Or can the argument be left undefined?

This can be quite annoying. I’d prefer if there was some kind dead bus number (perhaps negative values), but there isnt (to my knowledge).

Yes, make a large bus, like 10 channels, and use that as the initial value.

To help with this you could do this…
I’m on mobile, so this probably has some errors.

~default_bus = (\ar_bus :, 10), \kr_bus: Bus.control(s, 10));

~opt_bus = {  | rate, name |
   if(rate ==\ar, { ~default_bus[\ar_bus] )
   }, { ~default_bus[\kr_bus] )


x = { 
   var signal = ...; ~opt_bus.(\ar, \out), signal ) 

x.set(\out, 0);

Yeah I was also trying to see if setting as default SynthDef(\test,{ arg bus=Nil ; ... } would work, but Nil basically equates to 0. So now, i’ll create a ~nilbus=Bus.control(), and use that as a default for inputs.