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;;;  retention.lisp
;;;  Written by:  Shaul Markovitch
;;;  Last time modified: 10/1/2000
;;;
;;;  This file contains forgetting methods.  Currently we don't
;;;  call the forgetting procedure since forgetting (retention
;;;  filtering) can be performed as a seperate process. 
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(defclass retention-filter ()())

(defclass null-retention-filter (retention-filter)())

(defmethod forget-macros
    (macro-db (retention-method null-retention-filter) domain)
  (declare (ignore domain))
  macro-db)