diff --git a/src/functions/accumulator.ts b/src/functions/accumulator.ts
index bb8a7fb..0bef8e1 100644
--- a/src/functions/accumulator.ts
+++ b/src/functions/accumulator.ts
@@ -4,10 +4,11 @@ import {
     FlushStrategy,
     TransformOptions,
 } from "./baseDefinitions";
-import { batch } from ".";
+import { batch, rate as _rate } from ".";
 
 function _accumulator<T>(
     accumulateBy: (data: T, buffer: T[], stream: Transform) => void,
+    rate?: number,
     shouldFlush: boolean = true,
     options: TransformOptions = {
         readableObjectMode: true,
@@ -15,7 +16,7 @@ function _accumulator<T>(
     },
 ) {
     const buffer: T[] = [];
-    return new Transform({
+    const stream = new Transform({
         ...options,
         transform(data: T, encoding, callback) {
             accumulateBy(data, buffer, this);
@@ -28,11 +29,14 @@ function _accumulator<T>(
             callback();
         },
     });
+    if (rate) {
+        stream.pipe(_rate(rate));
+    }
+    return stream;
 }
 
 function _sliding<T>(
     windowLength: number,
-    rate: number | undefined,
     key?: string,
 ): (event: T, buffer: T[], stream: Transform) => void {
     return (event: T, buffer: T[], stream: Transform) => {
@@ -66,7 +70,6 @@ function _sliding<T>(
 }
 
 function _slidingByFunction<T>(
-    rate: number | undefined,
     iteratee: AccumulatorByIteratee<T>,
 ): (event: T, buffer: T[], stream: Transform) => void {
     return (event: T, buffer: T[], stream: Transform) => {
@@ -81,7 +84,6 @@ function _slidingByFunction<T>(
 }
 
 function _rollingByFunction<T>(
-    rate: number | undefined,
     iteratee: AccumulatorByIteratee<T>,
 ): (event: T, buffer: T[], stream: Transform) => void {
     return (event: T, buffer: T[], stream: Transform) => {
@@ -97,7 +99,6 @@ function _rollingByFunction<T>(
 
 function _rolling<T>(
     windowLength: number,
-    rate: number | undefined,
     key?: string,
 ): (event: T, buffer: T[], stream: Transform) => void {
     return (event: T, buffer: T[], stream: Transform) => {
@@ -129,58 +130,84 @@ function _rolling<T>(
 }
 
 export function accumulator(
-    batchSize: number,
-    batchRate: number | undefined,
     flushStrategy: FlushStrategy,
+    batchSize: number,
     keyBy?: string,
+    options: TransformOptions & { rate?: number } = {
+        readableObjectMode: true,
+        writableObjectMode: true,
+    },
 ): Transform {
     if (flushStrategy === FlushStrategy.sliding) {
-        return sliding(batchSize, batchRate, keyBy);
+        return sliding(batchSize, keyBy, options);
     } else if (flushStrategy === FlushStrategy.rolling) {
-        return rolling(batchSize, batchRate, keyBy);
+        return rolling(batchSize, keyBy, options);
     } else {
-        return batch(batchSize, batchRate);
+        return batch(batchSize, options.rate);
     }
 }
 
 export function accumulatorBy<T, S extends FlushStrategy>(
-    batchRate: number | undefined,
     flushStrategy: S,
     iteratee: AccumulatorByIteratee<T>,
+    options: TransformOptions & { rate?: number } = {
+        readableObjectMode: true,
+        writableObjectMode: true,
+    },
 ): Transform {
     if (flushStrategy === FlushStrategy.sliding) {
-        return slidingBy(batchRate, iteratee);
+        return slidingBy(iteratee, options);
     } else {
-        return rollingBy(batchRate, iteratee);
+        return rollingBy(iteratee, options);
     }
 }
 
 function sliding(
     windowLength: number,
-    rate: number | undefined,
     key?: string,
+    options?: TransformOptions & { rate?: number },
 ): Transform {
-    return _accumulator(_sliding(windowLength, rate, key), false);
+    return _accumulator(
+        _sliding(windowLength, key),
+        options && options.rate,
+        false,
+        options,
+    );
 }
 
 function slidingBy<T>(
-    rate: number | undefined,
     iteratee: AccumulatorByIteratee<T>,
+    options?: TransformOptions & { rate?: number },
 ): Transform {
-    return _accumulator(_slidingByFunction(rate, iteratee), false);
+    return _accumulator(
+        _slidingByFunction(iteratee),
+        options && options.rate,
+        false,
+        options,
+    );
 }
 
 function rolling(
     windowLength: number,
-    rate: number | undefined,
     key?: string,
+    options?: TransformOptions & { rate?: number },
 ): Transform {
-    return _accumulator(_rolling(windowLength, rate, key));
+    return _accumulator(
+        _rolling(windowLength, key),
+        options && options.rate,
+        true,
+        options,
+    );
 }
 
 function rollingBy<T>(
-    rate: number | undefined,
     iteratee: AccumulatorByIteratee<T>,
+    options?: TransformOptions & { rate?: number },
 ): Transform {
-    return _accumulator(_rollingByFunction(rate, iteratee));
+    return _accumulator(
+        _rollingByFunction(iteratee),
+        options && options.rate,
+        true,
+        options,
+    );
 }
diff --git a/src/functions/demux.ts b/src/functions/demux.ts
index 4b6312a..2a515ec 100644
--- a/src/functions/demux.ts
+++ b/src/functions/demux.ts
@@ -58,7 +58,21 @@ class Demux extends Writable {
             this.streamsByKey[destKey] = this.construct(destKey);
         }
         if (!this.streamsByKey[destKey].write(chunk, encoding)) {
+            console.log(
+                "waiting drain",
+                chunk,
+                this._writableState.length,
+                this.streamsByKey[destKey]._writableState.length,
+                this.streamsByKey[destKey]._readableState.length,
+            );
             this.streamsByKey[destKey].once("drain", () => {
+                console.log(
+                    "calling cb after drain",
+                    chunk,
+                    this._writableState.length,
+                    this.streamsByKey[destKey]._writableState.length,
+                    this.streamsByKey[destKey]._readableState.length,
+                );
                 cb();
             });
         } else {
diff --git a/src/functions/index.ts b/src/functions/index.ts
index 48d8062..778b1b9 100644
--- a/src/functions/index.ts
+++ b/src/functions/index.ts
@@ -171,10 +171,11 @@ export const parallelMap = baseFunctions.parallelMap;
  * 		When no key is provided, the batchSize is the buffer length. When a key is provided, the batchSize
  * 		is based on the value at that key. For example, given a key of `timestamp` and a batchSize of 3000,
  * 		each item in the buffer will be guaranteed to be within 3000 timestamp units from the first element.
+ * @param flushStrategy Buffering strategy to use.
  * @param batchSize Size of the batch (in units of buffer length or value at key).
  * @param batchRate Desired rate of data transfer to next stream.
- * @param flushStrategy Buffering strategy to use.
  * @param keyBy Key to determine if element fits into buffer or items need to be cleared from buffer.
+ * @param options Transform stream options
  */
 export const accumulator = baseFunctions.accumulator;
 
@@ -187,10 +188,11 @@ export const accumulator = baseFunctions.accumulator;
  * 	2. Rolling
  * 		- If the iteratee returns false, the buffer is cleared and pushed into stream. The item is
  * 		then pushed into the buffer.
- * @param batchRate Desired rate of data transfer to next stream.
  * @param flushStrategy Buffering strategy to use.
  * @param iteratee Function applied to buffer when a chunk of data enters stream to determine if element fits into
  * or items need to be cleared from buffer.
+ * @param batchRate Desired rate of data transfer to next stream.
+ * @param options Transform stream options
  */
 export const accumulatorBy = baseFunctions.accumulatorBy;
 
diff --git a/tests/accumulator.spec.ts b/tests/accumulator.spec.ts
index 71fdb1f..2ee455c 100644
--- a/tests/accumulator.spec.ts
+++ b/tests/accumulator.spec.ts
@@ -18,7 +18,7 @@ test.cb("accumulator() rolling", t => {
     const flushes = [firstFlush, secondFlush, thirdFlush];
 
     source
-        .pipe(accumulator(2, undefined, FlushStrategy.rolling))
+        .pipe(accumulator(FlushStrategy.rolling, 2))
         .on("data", (flush: TestObject[]) => {
             t.deepEqual(flush, flushes[chunkIndex]);
             chunkIndex++;
@@ -51,7 +51,7 @@ test.cb("accumulator() rolling with key", t => {
     const flushes = [firstFlush, secondFlush];
 
     source
-        .pipe(accumulator(3, undefined, FlushStrategy.rolling, "ts"))
+        .pipe(accumulator(FlushStrategy.rolling, 3, "ts"))
         .on("data", (flush: TestObject[]) => {
             t.deepEqual(flush, flushes[chunkIndex]);
             chunkIndex++;
@@ -77,9 +77,8 @@ test.cb(
         }
         const source = new Readable({ objectMode: true });
         const accumulatorStream = accumulator(
-            3,
-            undefined,
             FlushStrategy.rolling,
+            3,
             "nonExistingKey",
         );
         const input = [{ ts: 0, key: "a" }, { ts: 1, key: "b" }];
@@ -119,12 +118,7 @@ test.cb(
             key: string;
         }
         const source = new Readable({ objectMode: true });
-        const accumulatorStream = accumulator(
-            3,
-            undefined,
-            FlushStrategy.rolling,
-            "ts",
-        );
+        const accumulatorStream = accumulator(FlushStrategy.rolling, 3, "ts");
         const input = [
             { ts: 0, key: "a" },
             { ts: 1, key: "b" },
@@ -193,7 +187,7 @@ test.cb("accumulator() sliding", t => {
 
     const flushes = [firstFlush, secondFlush, thirdFlush, fourthFlush];
     source
-        .pipe(accumulator(3, undefined, FlushStrategy.sliding))
+        .pipe(accumulator(FlushStrategy.sliding, 3))
         .on("data", (flush: TestObject[]) => {
             t.deepEqual(flush, flushes[chunkIndex]);
             chunkIndex++;
@@ -248,7 +242,7 @@ test.cb("accumulator() sliding with key", t => {
         sixthFlush,
     ];
     source
-        .pipe(accumulator(3, undefined, FlushStrategy.sliding, "ts"))
+        .pipe(accumulator(FlushStrategy.sliding, 3, "ts"))
         .on("data", (flush: TestObject[]) => {
             t.deepEqual(flush, flushes[chunkIndex]);
             chunkIndex++;
@@ -274,9 +268,8 @@ test.cb(
         }
         const source = new Readable({ objectMode: true });
         const accumulatorStream = accumulator(
-            3,
-            undefined,
             FlushStrategy.sliding,
+            3,
             "nonExistingKey",
         );
         const input = [{ ts: 0, key: "a" }, { ts: 1, key: "b" }];
@@ -315,12 +308,7 @@ test.cb(
             key: string;
         }
         const source = new Readable({ objectMode: true });
-        const accumulatorStream = accumulator(
-            3,
-            undefined,
-            FlushStrategy.sliding,
-            "ts",
-        );
+        const accumulatorStream = accumulator(FlushStrategy.sliding, 3, "ts");
         const input = [
             { ts: 0, key: "a" },
             { key: "b" },
@@ -386,7 +374,6 @@ test.cb("accumulatorBy() rolling", t => {
     source
         .pipe(
             accumulatorBy(
-                undefined,
                 FlushStrategy.rolling,
                 (event: TestObject, bufferChunk: TestObject) => {
                     return bufferChunk.ts + 3 <= event.ts;
@@ -422,7 +409,6 @@ test.cb.skip(
             { ts: 2, key: "c" },
         ];
         const accumulaterStream = accumulatorBy(
-            undefined,
             FlushStrategy.rolling,
             (event: TestObject, bufferChunk: TestObject) => {
                 if (event.key !== "a") {
@@ -490,7 +476,6 @@ test.cb("accumulatorBy() sliding", t => {
     source
         .pipe(
             accumulatorBy(
-                undefined,
                 FlushStrategy.sliding,
                 (event: TestObject, bufferChunk: TestObject) => {
                     return bufferChunk.ts + 3 <= event.ts ? true : false;
@@ -526,7 +511,6 @@ test.cb.skip(
             { ts: 2, key: "c" },
         ];
         const accumulaterStream = accumulatorBy(
-            undefined,
             FlushStrategy.sliding,
             (event: TestObject, bufferChunk: TestObject) => {
                 if (event.key !== "a") {
diff --git a/tests/demux.spec.ts b/tests/demux.spec.ts
index 2d43ec1..370e117 100644
--- a/tests/demux.spec.ts
+++ b/tests/demux.spec.ts
@@ -379,6 +379,7 @@ test.cb.only(
         const construct = (destKey: string) => {
             const first = map(
                 (chunk: Chunk) => {
+                    console.log("1: ", chunk);
                     chunk.mapped.push(1);
                     return chunk;
                 },
@@ -387,7 +388,9 @@ test.cb.only(
 
             const second = map(
                 async (chunk: Chunk) => {
+                    console.log("2: ", chunk);
                     await sleep(slowProcessorSpeed);
+                    console.log("2 done ", chunk);
                     chunk.mapped.push(2);
                     return chunk;
                 },
@@ -408,6 +411,7 @@ test.cb.only(
         // This event should be received after at least 5 * slowProcessorSpeed (two are read immediately by first and second, 5 remaining in demux before drain event)
         _demux.on("drain", () => {
             expect(_demux._writableState.length).to.be.equal(0);
+            console.log(performance.now() - start);
             expect(performance.now() - start).to.be.greaterThan(
                 slowProcessorSpeed * (input.length - 2),
             );
@@ -427,7 +431,7 @@ test.cb.only(
 
         const start = performance.now();
         input.forEach(item => {
-            _demux.write(item);
+            console.log(_demux.write(item));
         });
     },
 );
@@ -457,6 +461,7 @@ test.cb(
         const construct = (destKey: string) => {
             const first = map(
                 (chunk: Chunk) => {
+                    console.log("1: ", chunk);
                     chunk.mapped.push(1);
                     return chunk;
                 },
@@ -464,6 +469,7 @@ test.cb(
             );
             const second = map(
                 (chunk: Chunk) => {
+                    console.log("2: ", chunk);
                     chunk.mapped.push(2);
                     return chunk;
                 },
@@ -472,7 +478,9 @@ test.cb(
 
             const third = map(
                 async (chunk: Chunk) => {
+                    console.log("3: ", chunk);
                     await sleep(slowProcessorSpeed);
+                    console.log(" 3 done ", chunk);
                     chunk.mapped.push(3);
                     return chunk;
                 },
@@ -496,6 +504,7 @@ test.cb(
         // This event should be received after at least 3 * slowProcessorSpeed (two are read immediately by first and second, 3 remaining in demux before drain event)
         _demux.on("drain", () => {
             expect(_demux._writableState.length).to.be.equal(0);
+            console.log(performance.now() - start);
             expect(performance.now() - start).to.be.greaterThan(
                 slowProcessorSpeed * (input.length - 4),
             );
@@ -515,7 +524,7 @@ test.cb(
 
         const start = performance.now();
         input.forEach(item => {
-            _demux.write(item);
+            console.log(_demux.write(item));
         });
     },
 );