chore(banner): update banner refs

README.md

@@ -28,7 +28,7 @@ material on the web. The goal is to supplement the
 while offering a new, fresh perspective to clear any hurdles and tackle the pain
 points. Learning Rx may be difficult but it is certainly worth the effort!
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Brand New to RxJS?
 
@@ -133,7 +133,7 @@ site, these excellent resources will help jump start your learning experience!
 
 #### Videos
 
-- [RxJS Basics](https://ultimatecourses.com/courses/rxjs) :dollar: - Brian
+- [RxJS Basics](https://ultimatecourses.com/courses/rxjs?ref=4) :dollar: - Brian
   Troncone
 - [Asynchronous Programming: The End of The Loop](https://egghead.io/courses/mastering-asynchronous-programming-the-end-of-the-loop) -
   Jafar Husain

operators/combination/combineall.md

@@ -4,7 +4,7 @@
 
 ## When source observable completes use [combineLatest](combinelatest.md) with collected observables.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/combinelatest.md

@@ -31,7 +31,7 @@ Lastly, if you are working with observables that only emit one value, or you
 only require the last value of each before completion, [`forkJoin`](forkjoin.md)
 is likely a better option.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/concat.md

@@ -14,7 +14,7 @@ instead!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/concatall.md

@@ -15,7 +15,7 @@ a single operator instead!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/endwith.md

@@ -14,7 +14,7 @@ value, check out [`finalize`](../utility/finalize.md)!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/forkjoin.md

@@ -35,7 +35,7 @@ item, and you are concerned with the previous emissions `forkJoin` is not the
 correct choice. In these cases you may be better off with an operator like
 [combineLatest](combinelatest.md) or [zip](zip.md).
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/merge.md

@@ -13,7 +13,7 @@ instead!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/mergeall.md

@@ -11,7 +11,7 @@ single operator instead!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/pairwise.md

@@ -4,7 +4,7 @@
 
 ## Emit the previous and current values as an array.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/race.md

@@ -4,7 +4,7 @@
 
 ## The observable to emit first is used.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/startwith.md

@@ -12,7 +12,7 @@ can also start with an initial value!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/withlatestfrom.md

@@ -11,7 +11,7 @@ emits, try [combinelatest](combinelatest.md)!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/combination/zip.md

@@ -12,7 +12,7 @@ source!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/conditional/defaultifempty.md

@@ -4,7 +4,7 @@
 
 ## Emit given value if nothing is emitted before completion.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/conditional/every.md

@@ -4,7 +4,7 @@
 
 ## If all values pass predicate before completion emit true, else false.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/conditional/iif.md

@@ -4,7 +4,7 @@
 
 ## Subscribe to first or second observable based on a condition
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/conditional/sequenceequal.md

@@ -4,7 +4,7 @@
 
 ## Compares emitted sequence to expected sequence for match
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/ajax.md

@@ -4,7 +4,7 @@
 
 ## Create an observable for an Ajax request with either a request object with url, headers, etc or a string for a URL.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/create.md

@@ -4,7 +4,7 @@
 
 ## Create an observable with given subscription function.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/defer.md

@@ -12,7 +12,7 @@ is used as part of the [`iif`](../conditional/iif.md) operator!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/empty.md

@@ -4,7 +4,7 @@
 
 ## Observable that immediately completes.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/from.md

@@ -16,7 +16,7 @@ characters!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/fromevent.md

@@ -4,7 +4,7 @@
 
 ## Turn event into observable sequence.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/generate.md

@@ -4,7 +4,7 @@
 
 ## Generates an observable sequence by running a state-driven loop producing the sequence's elements, using the specified scheduler to send out observer messages.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/interval.md

@@ -4,7 +4,7 @@
 
 ## Emit numbers in sequence based on provided timeframe.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/range.md

@@ -4,7 +4,7 @@
 
 ## Emit numbers in provided range in sequence.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/throw.md

@@ -4,7 +4,7 @@
 
 ## Emit error on subscription.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/creation/timer.md

@@ -4,7 +4,7 @@
 
 ## After given duration, emit numbers in sequence every specified duration.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/error_handling/catch.md

@@ -10,7 +10,7 @@
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/error_handling/retry.md

@@ -15,7 +15,7 @@
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/error_handling/retrywhen.md

@@ -4,7 +4,7 @@
 
 ## Retry an observable sequence on error based on custom criteria.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/debounce.md

@@ -11,7 +11,7 @@
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/debouncetime.md

@@ -11,7 +11,7 @@ of user input must be controlled!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/distinct.md

@@ -4,7 +4,7 @@
 
 ## Emits items emitted that are distinct based on any previously emitted item.
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/distinctuntilchanged.md

@@ -14,7 +14,7 @@ must match!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/distinctuntilkeychanged.md

@@ -4,7 +4,7 @@
 
 ## Only emit when the specified key value has changed
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/filter.md

@@ -11,7 +11,7 @@ out [takeWhile](takewhile.md)!
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples
 

operators/filtering/find.md

@@ -11,7 +11,7 @@
 
 ---
 
-<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
+<div class="ua-ad"><a href="https://ultimatecourses.com/courses/rxjs?ref=4"><img src="https://drive.google.com/uc?export=view&id=1htrban3k3Z8CxiKwEV6bdmxW5Wu8xdWX" style="width:100%;max-width:100%"></a></div>
 
 ### Examples