code: function mergeScan(accumulator, seed, concurrent) {
      if (concurrent === void 0) {
          concurrent = Number.POSITIVE_INFINITY;
      }
      return function (source) { return source.lift(new MergeScanOperator(accumulator, seed, concurrent)); };
  }
docs: PURE_IMPORTS_START tslib,_util_tryCatch,_util_errorObject,_util_subscribeToResult,_OuterSubscriber PURE_IMPORTS_END