(define (domain holes)
  (:requirements :strips :typing)
  (:types type)
  (:predicates (empty ?hole) (out ?pigeon) (in ?pigeon ?hole) (placed ?pigeon))
  (:action fill
    :parameters (?hole ?pigeon)
    :precondition (and (empty ?hole)
		       (out ?pigeon) 
		  )
    :effect  (and (in ?pigeon ?hole)
		  (placed ?pigeon)
		  (not (out ?pigeon))
		  (not (empty ?hole))))
  )