# File lib/rbrainz/webservice/filter.rb, line 209
      def initialize(filter)
        Utils.check_options filter, 
            :limit, :offset, :query, :title, :artist, :release, :duration, 
            :tracknum, :artistid, :releaseid, :puid, :count, :releasetype
        super(filter)
        @filter[:title]       = filter[:title]     if filter[:title]
        @filter[:artist]      = filter[:artist]    if filter[:artist]
        @filter[:release]     = filter[:release]   if filter[:release]
        @filter[:duration]    = filter[:duration]  if filter[:duration]
        @filter[:tracknum]    = filter[:tracknum]  if filter[:tracknum]
        @filter[:artistid]    = filter[:artistid]  if filter[:artistid]
        @filter[:releaseid]   = filter[:releaseid] if filter[:releaseid]
        @filter[:puid]        = filter[:puid]      if filter[:puid]
        @filter[:count]       = filter[:count]     if filter[:count]
        if filter[:releasetype]
          @filter[:releasetype] = Utils.remove_namespace(filter[:releasetype])
        end
      end