Possible purpose of extra, unused arg in call to method in an efslib

[rlewkov]

Hello,
I've looked at someone's efs indicator code which calls methods in an efslib. Here's a snippet ...

// In the indicator efs
var myLibrary = addLibrary("someLibrary.efsLib");

aNumber=100;
retVal=myLibrary.methodA(aNumber);

// In someLibrary.efsLib
function methodA(aNum, _arg) {
return (efsInternal("_methodA", aNum, _arg));
}

My question:
In the efsLib, methodA has a last argument of "_arg".
This value is not present in the call to methodA in the efs indicator.
In the efsLib this arg is further passed to other functions called from _methodA though it's never referenced anywhere it's passed to.
So, this argument, though present in the argument list of methodA, is not passed in when methodA is called nor is it used anywhere that it's passed to.
The indicator works just fine.

So, why might this arguement exist? What could be its purpose? Is it some lightly-documented feature?
I couldn't find anything on the eSignal site that suggests an answer.

Thanks