docs: function parseFilePage(book, filePath) {
      var fs = book.getContentFS();
  
      return fs.statFile(filePath)
      .then(
          function(file) {
              var page = Page.createForFile(file);
              return parsePage(book, page);
          },
          function(err) {
              // file doesn't exist
              return null;
          }
      )
      .fail(function(err) {
          var logger = book.getLogger();
          logger.error.ln('error while parsing page "' + filePath + '":');
          throw err;
      });
  }