docs: function transform(context, settings, next) {
    var fileSet = new FileSet()
  
    context.fileSet = fileSet
  
    fileSet.on('add', add).on('done', next)
  
    if (context.files.length === 0) {
      next()
    } else {
      context.files.forEach(fileSet.add, fileSet)
    }
  
    function add(file) {
      filePipeline.run(
        {
          configuration: context.configuration,
          processor: settings.processor(),
          cwd: settings.cwd,
          extensions: settings.extensions,
          pluginPrefix: settings.pluginPrefix,
          treeIn: settings.treeIn,
          treeOut: settings.treeOut,
          inspect: settings.inspect,
          color: settings.color,
          out: settings.out,
          output: settings.output,
          streamOut: settings.streamOut,
          alwaysStringify: settings.alwaysStringify
        },
        file,
        fileSet,
        done
      )
  
      function done(error) {
        /* istanbul ignore next - doesn’t occur as all
         * failures in `filePipeLine` are failed on each
         * file.  Still, just to ensure things work in
         * the future, we add an extra check. */
        if (error) {
          error = file.message(error)
          error.fatal = true
        }
  
        fileSet.emit('one', file)
      }
    }
  }