docs: function (self, args) {
      var root, pathname = args[0] || '.', stat;
  
      if (isAbsolute(pathname)) {
        throw new Error('require_directory argument must be a relative path');
      }
  
      root = path.resolve(path.dirname(self.pathname), pathname);
      stat = self.stat(root);
  
      if (!stat || !stat.isDirectory()) {
        throw new Error('require_directory argument must be a directory');
      }
  
      self.context.dependOn(root);
  
      _.forEach(self.entries(root), function (pathname) {
        pathname = path.join(root, pathname);
  
        if (self.file === pathname) {
          return;
        } else if (self.context.isAssetRequirable(pathname)) {
          self.context.requireAsset(pathname);
        }
      });
    }