    # File lib/compass/sprite_importer.rb, line 88
        def self.sprite_names(uri)
          files(uri).collect do |file|
            filename = File.basename(file, '.png')
            unless VAILD_FILE_NAME =~ filename
              raise Compass::Error, "Sprite file names must be legal css identifiers. Please rename #{File.basename(file)}"
            end
            filename
          end
        end