# File lib/hammer_cli_import/persistentmap.rb, line 109
    def load_persistent_maps
      @pm = {}
      maps.each do |map_sym|
        hash = {}
        Dir[File.join data_dir, "#{map_sym}-*.csv"].sort.each do |filename|
          reader = CSV.open(filename, 'r')
          header = reader.shift
          raise PersistentMapError, "Importing :#{map_sym} from file #{filename}" unless header == (pm_csv_headers map_sym)
          reader.each do |row|
            key, value = pm_decode_row map_sym, row
            delkey = row[-1] == '-'
            if delkey
              hash.delete key
            else
              hash[key] = value
            end
          end
        end
        @pm[map_sym] = add_checks(DeltaHash[hash], self.class.map_description[map_sym], map_sym)
      end
    end