code: function getWithFallback (id) {
  
              if (!this.isReady) {
                  throw new L10nError('Context not ready');
              }
  
              var cur = 0;
              var loc;
              var locale;
              while (loc = this.supportedLocales[cur]) { // eslint-disable-line no-cond-assign
                  locale = this.getLocale(loc);
                  if (!locale.isReady) {
                      // build without callback, synchronously
                      locale.build(null);
                  }
                  var entry = locale.getEntry(id);
                  if (entry === undefined) {
                      cur++;
                      warning.call(this, new L10nError(id + ' not found in ' + loc, id,
                          loc));
                      continue;
                  }
                  return entry;
              }
  
              error.call(this, new L10nError(id + ' not found', id));
              return null;
          }
docs: Getting translations