# File lib/rbrainz/webservice/filter.rb, line 98
      def initialize(filter)
        Utils.check_options filter, 
          :limit, :offset, :query, :title, :artist, :artistid, :releasetypes
        super(filter)
        @filter[:title]        = filter[:title]     if filter[:title]
        @filter[:artist]       = filter[:artist]    if filter[:artist]
        @filter[:artistid]     = filter[:artistid]  if filter[:artistid]
        
        if releasetypes = filter[:releasetypes]
          if releasetypes.respond_to?(:to_a)
            releasetypes = releasetypes.to_a.map do |type|
              Utils.remove_namespace(type)
            end.join(' ')
          end
          @filter[:releasetypes] = releasetypes
        end
      end