Scalar getScalar(ListingActionContext context) {
		CodeUnit cu = getCodeUnit(context);
		Scalar scalar = getScalar(cu, context);
		return scalar;
	}
Get the operand index at the location
@param context the action context
@return 0-3 for a good operand location, -1 otherwise
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/equate/EquatePlugin.java