* (defgeneric yet-another-fn (obj1 obj2))
#<STANDARD-GENERIC-FUNCTION YET-ANOTHER-FN (0) {584D9EC9}>

* (defmethod yet-another-fn ((obj1 class-a) obj2) :first-arg-specialized)
#<STANDARD-METHOD YET-ANOTHER-FN (CLASS-A T) {5854269D}>

* (defmethod yet-another-fn (obj1 (obj2 class-b)) :second-arg-specialized)
#<STANDARD-METHOD YET-ANOTHER-FN (T CLASS-B) {585AAAAD}>

* (yet-another-fn (make-instance 'class-a) (make-instance 'class-b))
:FIRST-ARG-SPECIALIZED