A variadic argument list. The first argument (args[0]) is the optional
value parameter. Its presence is detected via args.length, allowing
the function to distinguish between an explicitly passed undefined value
and a completely omitted argument.
Whether the passed value features a stable type-identity.
Does approve whether the passed value features a stable type-identity, which is ... either the value comes with the built-in type-identity of one of the core language's types, or the value has been processed via
defineStableTypeIdentity, or it features property-descriptors which are in line with the result of the latter process.