code: function load (opts, cb) {
      var file;
      if (typeof opts === 'string') {
          file = opts;
          opts = {};
      } else {
          file = opts.file;
      }
  
      // try cache
      if (!opts.force && load.cache[file]) {
          process.nextTick(function () {
              cb(null, load.cache[file]);
          });
          return;
      }
  
      FS.readFile(file, 'utf-8', function (err, data) {
          load.cache[file] = data;
          cb(err, data);
      });
  }
docs: Caching loader some native file
  @param {String|{file: String, force: Boolean}} opts filename or object with filename and options
  @param {Function} cb