@Override
		protected void initFinished() {
			if (posIns == -1) {
				throw new IllegalArgumentException(
					"Variadic userop must have a parameter for the inputs");
			}
		}
An annotated userop with a variable number of arguments

@param <T> the type of data processed by the userop
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/AnnotatedPcodeUseropLibrary.java