def download(target, options = {})
      case target
      when String
        modified = File.stat(target).mtime if File.exist?(target)
        temp = nil
        Tempfile.open(File.basename(target)) do |tf|
          tf.binmode
          read(options.merge(:modified => modified)) { |chunk| tf.write chunk }
          temp = tf
        end
        FileUtils.mkpath(File.dirname(target))
        FileUtils.move(temp.path, target)
      when File
        p options.merge(:modified => target.mtime)
        read(options.merge(:modified => target.mtime)) { |chunk| target.write chunk }
        target.flush
      else
        raise ArgumentError, "Expecting a target that is either a file name (string, task) or object that responds to write (file, pipe)." unless target.respond_to?(:write)
        read(options) { |chunk| target.write chunk }
        target.flush
      end
    end