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‫All right. This lecture is starting off where the last one

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‫ended. So, if you're just jumping into this one and you

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‫skipped the last one, go back to that one because you'll

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‫need the Deployment that we created in that one

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‫to start this one.

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‫When I do a kubectl get all, I

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‫should see here that I have one Deployment

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‫that has a replica set of five.

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‫You'll see the five pods.

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‫Then you'll have the Kubernetes default service,

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‫which is always there. Then the httpenv

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‫cluster IP service.

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‫You, of course, may have different IP addresses and

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‫different pod names. That's where we need to be.

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‫We have this Deployment.

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‫We've created an IP address inside the cluster for others

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‫to access it with the friendly name of httpenv

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‫because that's the service name.

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‫Let's create one that's exposed externally on

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‫the host IP. This would be, if you were maybe in

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‫a data center or somewhere that you didn't have a load

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‫balancer you could control with the load balancer

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‫service, which we'll talk about a minute.

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‫You just basically, in this case, want to do a NodePort

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‫where you get ports somewhere in the high range

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‫of your Kubernetes cluster that you can

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‫use to talk from the outside in.

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‫So it will be able to access it from some external

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‫service, right. It's not going to be on port 80 by default.

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‫The NodePorts are meant to be high ports so you're usually

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‫putting something in front of that, like an external load

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‫balancer or some automated service that will manage

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‫that for you. In this case, I can do a

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‫kubectl expose again.

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‫It's going to look like the last one we did.

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‫deployment httpenv.

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‫That's the one we need to expose.

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‫We're going to put in port 8888 again.

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‫But, we're going to give it a new name because we already

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‫have one called httpenv.

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‫So, this one we're going to call a

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‫httpenv-np for no port.

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‫That way, it will work side by side with

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‫the cluster IP one that's already there.

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‫Then we're going to change the type to NodePort.

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‫You'll notice that type of NodePort, because the default

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‫type, which we can specify manually if you want to.

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‫The default type is cluster IP.

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‫If I go back and do a kubectl get

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‫services, you'll

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‫see a new one there that's type NodePort.

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‫Let's talk about the ports on the right.

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‫Those ports, when they have the colon in the middle, are

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‫the opposite of what you would see in Docker and Swarm.

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‫The port on the left, in this case, is

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‫the one inside the cluster, inside the

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‫container itself that's listing.

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‫Then the port on the right is the port that's on

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‫your nodes exposed to the outside world.

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‫You might wonder where the port on the right came from.

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‫That port is from a default range

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‫for NodePorts that are preset inside your container

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‫cluster.

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‫It's a high range. The hope here is that there's

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‫no conflicts, right. That there's nothing else on your

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‫system, by default, running on those ports.

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‫Because often the low ports, like 8888, are

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‫common enough that they might be used by something else. Then any

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‫ports in the really low range are

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‫usually only accessible by root. Ports 1024 and below.

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‫There's a few things to note here.

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‫The first one is you'll see the cluster IP.

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‫Even though when we created this NodePort

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‫service, we didn't say cluster IP.

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‫We said NodePort.

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‫These services are additive.

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‫What that means is it's starting with cluster IP, and

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‫then going to NodePort, and then to the load balancer

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‫optional service. Each one of them will create the

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‫services above it in this list.

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‫Which means that when I create a NodePort, it

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‫creates a cluster IP endpoint for me because

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‫that's how it connects. It takes the connection coming into

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‫that port on the high port of the node and then it

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‫redirects it to the cluster IP for that service.

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‫Of course, like most things in Kubernetes, all this is

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‫changeable and customizable.

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‫One of the things you can change is the port range.

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‫One of them is you can avoid the cluster IP.

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‫A lot of that stuff you can do, but most of it

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‫you can only do in YAML, which we will get to later.

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‫When you're doing stuff at the command line like this,

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‫we're limited on the number of options we can use.

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‫If you go beyond what those options allow, you're going

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‫to need to start doing YAML. We'll talk about that later in

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‫the course. OK. If you're on Linux, this

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‫NodePort is accessible on localhost now.

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‫So, you can use localhost, or the host IP itself, to

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‫cURL this port. Whatever port you have.

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‫It's probably not going to be the same port as mine since

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‫mine's 32334.

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‫If you're on Docker Desktop, it

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‫will provide a convenience layer with something called

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‫vpnkit that's just built into Docker Desktop where

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‫it will connect this to the localhost on your Windows or

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‫Mac machine.

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‫I can sit here on my Mac and cURL

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‫localhost 32334.

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‫I get back that same response as if I cURLed the cluster

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‫IP directly. The reason that this is here on

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‫Docker Desktop is so that you don't have to jump into those

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‫pods like we did earlier just so that you can access the

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‫service. This is one way to have your Kubernetes services

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‫shown up on your machines so that you can test things,

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‫right. So, if you're developing or testing inside

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‫Kubernetes, you can then just do a NodePort

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‫and go to that port, which is going to be a little random

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‫on your host.

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‫Again, you can specify an exact port there,

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‫but you'd have to do that in YAML, which we'll do later.

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‫The other option, if you're on Docker Desktop, is that it

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‫comes with a built-in load balancer service.

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‫You remember me talking earlier when we were talking about

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‫these four types of services, is that the load balancer

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‫wasn't built in, by default, and the only way you could use

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‫it was through an external service, usually in

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‫a cloud service, right.

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‫With Amazon, that would be ELBs and ALBs.

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‫With DigitalOcean, that would be with their load balancers.

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‫You would need to add that plugin in your Kubernetes so it

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‫would work with those external load balancers.

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‫Essentially, the kube API talks to their API

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‫to control that load balancer.

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‫If you're on Docker Desktop, then you can try this command.

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‫We'll call it httpenv-lb

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‫for this service, and we'll change the type to load

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‫balancer.

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‫If we do a kubectl get service, we should see three

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‫load balancers for this Deployment.

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‫Again, if you're on Docker Desktop, you'll be able to see

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‫all three. If you're on Linux, or using

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‫Minikube, or something like that, you would only see two.

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‫Each load balancer, because it's technically like a

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‫third-party plugin or service that's a remote API, the

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‫load balancers will all have varying features and supported

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‫stuff. You can sort of look at their documentation to

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‫figure out what they'll do.

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‫In this case, with Docker Desktop, all we did is we told

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‫it the port 8888 that was a

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‫part of the Deployment, and the load balancer service

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‫plugin from Docker will then publish it

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‫on port 8888.

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‫The nice thing here is that that is the one way

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‫to have your Kubernetes on a specific port

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‫outside of the default set, right.

156
00:07:19,780 --> 00:07:22,959
‫So, when we did the NodePort, we were defined,

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‫or limited, to that set in the 30000

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‫range. If you wanted to do something like you would with

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00:07:28,570 --> 00:07:31,265
‫Compose, or Swarm, or Docker run locally where you just

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00:07:31,600 --> 00:07:34,240
‫want to run it on a port like 80 or whatever,

161
00:07:34,840 --> 00:07:37,485
‫you can now with Docker Desktop, using the built-in

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‫Kubernetes, you can do that load balancer and just type

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00:07:41,080 --> 00:07:43,420
‫in that port there, and it will be responsive there.

164
00:07:43,450 --> 00:07:46,187
‫Now on Mac or Windows, I could type cURL

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00:07:47,410 --> 00:07:50,439
‫localhost 8888 and get

166
00:07:50,440 --> 00:07:52,659
‫that response back. You'll notice there for the load

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00:07:52,660 --> 00:07:55,690
‫balancer that it still has that other port.

168
00:07:55,750 --> 00:07:58,151
‫Again, that's because the 32 range there, on mine

169
00:07:58,930 --> 00:08:01,660
‫at least, is the built in

170
00:08:02,080 --> 00:08:04,149
‫NodePort that it's creating. Technically in the background,

171
00:08:04,150 --> 00:08:06,609
‫remember these are three different layers so the load

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00:08:06,610 --> 00:08:09,220
‫balancer is accepting my packet, then passing it to the

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00:08:09,610 --> 00:08:12,099
‫NodePort, and then the NodePort is passing it to the

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00:08:12,100 --> 00:08:14,950
‫cluster IP. There's always going to be that

175
00:08:15,670 --> 00:08:18,279
‫NodePort shown there next to the

176
00:08:18,670 --> 00:08:21,218
‫four 8's for a load balancer, even though that's not

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00:08:21,640 --> 00:08:24,142
‫really the port the load balancer is using on my localhost.

178
00:08:24,940 --> 00:08:26,979
‫Before going to the next lecture, let's clean up everything

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00:08:26,980 --> 00:08:29,079
‫we just did. We created a lot of stuff.

180
00:08:29,470 --> 00:08:31,989
‫These commands show you that you can use the delete command

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00:08:31,990 --> 00:08:33,729
‫with multiple objects at the same time.

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00:08:33,789 --> 00:08:35,349
‫They don't have to be related objects.

183
00:08:35,590 --> 00:08:37,209
‫In fact, you could just make a big list of them if you

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00:08:37,210 --> 00:08:38,409
‫wanted on a single command.