code: function getBook(args, kwargs) {
      var input = path.resolve(args[0] || process.cwd());
      var logLevel = kwargs.log;
  
      var fs = createNodeFS(input);
      var book = Book.createForFS(fs);
  
      return book.setLogLevel(logLevel);
  }
docs: Return a book instance to work on from
  command line args/kwargs
  
  @param {Array} args
  @param {Object} kwargs
  @return {Book}