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Let's not look at how we can create our own exceptions in the process we will also look at four very

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important suggestions from effective giallo unheeded the four items that we are going to discuss and

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discuss all these items include we will discuss the first two items in this lesson and the last two

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will be discussed in the follow up lessons and the first one is item 58 and it says use checked exceptions

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for recoverable conditions on runtime exceptions for programming it has to be under to discuss this

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.

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But I will discuss it in the context of creating new exception class itself.

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Second one is straightforward underdosed items have to fly under sists not to ignore exceptions people

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often by late date by using empty Gutch box which defeats the purpose of exceptions items is that ignoring

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an exception is similar to ignoring a fire alarm third and fourth items will be discussed later.

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And also supplemental notes will include a summary of all main points covering these items.

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So let's go ahead and extend no exceptions Democritus

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here we are in the Send method within the history class and we know that this method is responsible

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for the actual shooting of the data with the partner.

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And there are two ways to do it and we would be focusing on the second approach which is to pass the

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data in a pragmatic way via web service.

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And that happens if destination is equal to one and did a couple of genius to be made here and this

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method one off them as the data type here.

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Often there is a recurrent type has been changed from white to string.

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And the reason for that is we just want it done the response that we get from the web service.

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So the reps overstates the take somebody doesn't put a target and some response OK.

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Like whether it's whether that data has been processed successfully or not.

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And we just want to pretend that the doctor does to the working mother.

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So here is one variable the variable which which is going to read and the value of it is initial estimates

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success and it is really initialized here hear the response that we get from the web service.

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Now we're not doing the actual web service interrogation so let's just assume that this is the response

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that we got from the service.

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OK.

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So it's an example response.

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And here is the root element which is it isn't and within that we have court and within court there

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is this value I call success.

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OK now let's assume that according to the API contract exhumed this was supposed to be a numeric value

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Rexy all these days it was you know Mark uncertainly at this point of time when we made the invocation

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did attend and non-numeric value string.

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OK.

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So basically they broke the API contract and this is done going to affect us as it really big our court

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also.

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So they shouldn't have done this but trust me in my experience with several teams usually most of the

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time they don't.

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Most of the teams that I work with they never change the API in this way.

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But sometimes there were beams which did change the API that broke the cord that broke my cord.

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So it can happen sometimes.

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So that's when you're working with some unprofessional diems.

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So you shouldn't be doing that.

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So once the API is out you shouldn't change the response or even the request format.

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So in case you want to change it you have to let your clients know in advance and or set two or three

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weeks in advance so that they can make the necessary adjustments.

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So if you're doing something you don't amend just don't change the API Midway.

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Just make sure that your clients are informed in advance.

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So here is their response and we are reading the response here.

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Let's go back to exceptions to all this is a shared method from where we are in Woking.

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So here is the response.

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So it's getting assigned to this response variable.

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A new class has been written.

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API parser it's responsible for parsing the response on extracting individual data from it.

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So it's a different component here and there is a new method within that.

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It's Carlos parse send response code.

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So it's going to take the response here as an in book.

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It's going to extract the value of the code element.

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OK.

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So there wasn't anyone called court and it's going to extract that.

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And you're also passing these two values.

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Hello Aaron goodness which one also passed here to the Send method.

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And literally will see why we need that.

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OK.

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So let's just going do this mattered here.

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Here it is.

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So this matter is going to return the actual response.

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OK so it's going since it's supposed to be a numeric value.

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So it's going to return.

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And here so it's initialized or minus one.

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And here is a card which is going to extract the the value off the code element.

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OK.

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So just don't worry about it you can look at it later.

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But all it is doing is it is going to extract the code on in order to extract the code.

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I mean it has it does extract extracting court but in order to convert it to and we are using the parse

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and matured from the entire class.

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Now this is going to generate an exception because the value is non-numeric right.

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No because they have changed the API response but since we are a professional quarters we have a cricut

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Sheir.

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We want to because we want to handle it.

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So let's bring it here it's printable you and it's going to give us an exception.

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As you can see it says Number four marked exception because the input string is success.

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So it has been broken not so now.

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Let's create a new exception and throw that exception here so on later I will explain why.

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Why do we need to create a new exception.

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Why not simply propagate this exception so that will be disclosed in a later lesson which is also it

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which basically is about one of the items that we are supposed to discuss.

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So let's just go ahead and create a new exception since it's going to be an exception type of exception

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.

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So it has to extend one of the exception classes.

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Right.

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So let's just go ahead and do that since the API has changed.

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Let's name the exception in a meaningful way and let's call it as API for might change exception.

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Not we are going to look at a couple of suggestions from item 58 which is about you know would suggest

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that we need to use checked exceptions if you want to recover from the exception or runtime exceptions

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.

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And if it isn't programming programming it or know we can do we can do an extra here.

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Now we can also extend another.

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But the item is that we should not extend or we should not subclass it.

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And that's because there is a strong convention that errors should be generated only by JVM because

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they are JVM related.

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Under normal conditions.

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So the items are just that we should not be doing that.

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We should not be extending that ours.

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So there's a strong convention for that if you want to you can do it but we shouldn't be doing it.

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And that's that's the recommendation from the item now.

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So if this is all good then we can do it on time exception.

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That's one thing we can do.

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In fact you might want to do that because this is a programming error.

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The program is not written you know.

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He hasn't doubled up this particular piece of art.

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It's coming from an extra source but still you know it's kind of it's kind of a different component

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even though it's a different satirise from an extra partner you can think of it as a different component

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.

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And so it's basically you have to be a programming error from though from somebody in the partner site

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so it can be an exception.

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But the thing is in this particular case I think it would make sense to make it that checked exception

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in because runtime exception is an unchecked exception on by making a checked exception by throwing

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a check the exception.

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Are going to force the code that is going to invoke this particular method to handle it for sure.

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Right.

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So that's what will happen.

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If we make it a checked exception and the benefit of that is decline here and the exceptions to we'll

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have to catch it and let's say if in the future if there is another developer who for whatever reason

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.

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If you delete that Gorder then the compiler will inform him that they need to provide an exception handling

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core.

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And if it is a runtime exception since it would be an unchecked exception the compiler will not force

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them to do it.

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So it makes sense to force the hour hour hour and a person to actually handle that exception.

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And the way they can handle it is either by e-mailing the system administrator or one of their own uppers

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so that they can take some action they can inform the partner team that they need to fix the API.

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So it makes sense to to make this an exception.

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And if you want to make it a checked exception it cannot.

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We cannot subclass an exception or we cannot subclass error so we can either subclass an exception or

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any of its applauses or we can subclass tol'able.

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But the item also says that it's not recommended to extend to all.

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OK.

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So there definitely to indict them definitely recommends that.

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And the reason for that is it's just a little bit more confusing for the users.

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So they suggested that if you want to extend if you want to create a checked exception you can either

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subclause exception class which is their direct subclass of the open or one off it's subclasses one

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of the exception classes subprocess.

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So let's just go ahead and extend this.

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So that's all we have here.

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So not to go on as you know this needs to go in that cross-class So those are the those are some suggestions

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from item 58.

149

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So here it's go back into exceptions Demel we have an exception here because we need to handle it now

150

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.

151

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So there is already some quarter done here

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so it needs to be hundred.

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But a lot of times people also just how much blogs so they ignore the exception are an item fifty sixty

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five say is that we should not do that.

155

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Don't ignore the exceptions.

156

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Because here around here there is you know is making a statement that you need to handle it.

157

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And if you haven't time to catch block then you're defeating the purpose.

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And the item says that if if an exception if you're ignoring an exception like ignoring gun fired not

159

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him so you shouldn't be doing that because even if you ignore it sometimes you may be fined many times

160

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you may be fined but sometimes the results can be disastrous.

161

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Sometimes the results may not be immediately evident.

162

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Maybe the error might happen you know at a later point or find some other kind of gold under time it

163

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might be difficult to figure out the actual reason why the exception has been thrown because it's on

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it's happening at a completely different location.

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OK.

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So you shouldn't be ignoring exceptions with them to catch blocks and even if you want to do that at

167

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least you need to put some kind of a comment here stating why you are why you are not handling it why

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it is an empty catch block.

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OK so now let's just go ahead and let me also him this uncommented executer as you can see it says an

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API for matching exception and gives to doctoress.

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So those are the two items.

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Item 65 1958.

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Next we will look at item 63.

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And here we have this stack grease.

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But sometimes the issue is not reproducible so it will be difficult for the programmer to fix it.

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So item 63 is about how we can address doc.

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OK.

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So that's important and I'll see you in the next lesson.

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Item 63.

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Thank you.