code: function loadDocument (directory, callback) {
    var docPath = path.resolve(directory, '_design.js')
    fs.stat(docPath, function (err, stat) {
      if (err) return callback.call(null, err);
      if (stat.isFile()) {
        var document = require(docPath);
        return callback.call(null, null, document);
      }
      return callback.call(null, new Error('No _design.js file found!'));
    });
  }
docs: Load a design document from the _design.js directive
  within a specified directory.
  
  @param {string} directory
  @param {function} callback (err, document)