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This lecture is one of the most important lectures of the entire course, so don't miss it if you are

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able to understand what I'm talking about in this lecture.

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I'm pretty sure you will succeed with Python.

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So I'm going to talk about the anatomy of the Python programming language.

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Part of this video will be a summary of what you have learned so far.

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So I'll be going over the concepts you have learned and review them and explain them from another perspective

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so that you can see things from a different angle.

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Let's start.

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The first thing I want you to understand is that a program.

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It's like a place in the real world.

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Let's say a cafe.

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Things happen in a program.

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Things happen in a cafe.

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In the program.

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You are the programmer in the cafe.

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It's again you who orders a coffee, who orders a salad, etc..

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For example, to order a coffee in the cafe.

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You use the older coffee function, so to say.

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To order a list of to the items in the program you use the get.

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To do this function.

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You tell the function that to dos the text file as a string.

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In the case of ordering a coffee, you tell.

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This function that you want a coffee?

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You tell if it's going to be a short coffee or long and maybe you tell this function how many coffees

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you want.

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Let's say you want to.

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But so far, so good.

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This is clear.

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Now, here is the thing, and this is about understanding what actually types are in Python.

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So the data types, I've been talking about data types, but you can also refer to them as types this

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to this function.

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Gives us.

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A list of two dos.

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So first to do, second to do item, etc..

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Well, this function here gives us a coffee.

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Maybe in the cafe.

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You also use other functions such as the P function as inputs.

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You give money.

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As output.

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You get a receipt.

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Maybe you also use another function such as Clean the table.

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So you ask for a clean service from the waiter.

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And in this case.

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You don't get an output.

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Same here.

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We have this right to do function.

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This also doesn't give us an output, as you see.

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We are not returning anything in here.

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As we do in the get to this function.

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So this get to those functions gives us a an instance of a list.

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Now here is where you should make the distinction.

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I said an instance of a list, not a list itself.

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We usually say this gives us a list, but the list itself.

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It's an abstract concept.

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The same is true for coffee.

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Or sipped.

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So all these are abstract concepts.

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The actual objects are this instance that we got here, the receipt which says probably €10 or $10.

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This coffee is an instance.

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Also the coffee.

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Could be bitter, could be warmer, sometimes could be hotter other times.

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So there are different instances of coffee.

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The concept itself, this one here is just an abstract in our minds.

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Same goes for sipped.

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Same goes for list.

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So saying that I'm drinking a coffee or I'm buying a pan is technically wrong.

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What we should be saying is I'm drinking an instance of a coffee or I'm buying an instance of a pen.

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You can say I invented the pen.

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That could make sense.

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You invented the pen concept.

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And then people buy instances of that pen.

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So these concepts in Python are also called classes.

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Subtypes or classes types or classes are used interchangeably to terms.

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So you can say this is a type, but you can also say this is a class.

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So it is a blueprint.

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Just like coffee is a blueprint in our minds.

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And we know how to make instances of coffee by having that coffee in our mind, that abstract concept

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in our minds.

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So same goes for lists and same goes for strings.

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Another example, we implemented this pause function.

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So that is another example of a function in programming.

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This POS function got a string such as six feet 12 inches and it returned.

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A dictionary instance with keys and values.

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So dictionaries are also.

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Instances of this dictionary.

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Class.

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So just like we have different types of classes in the real world.

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Such as coffee received.

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We have different types of classes in a program.

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By the way, this year, when you say coffee or when you say short and when you say two.

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These are also instances.

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So coffee.

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This here is an instance of speech you can say or.

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You can say words.

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So just like we have a string here, a string is also a class, and this is an instance of a string

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to do the task.

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This is also an instance of a word or a speech you can say, and the number is also an instance of a

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word.

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So you give words to this function over coffee and you get an actual cup of coffee, an instance of

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the coffee class.

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Now all these instances.

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So this coffee or another coffee, they all have their own methods.

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So you can drink a coffee.

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You can sweeten it.

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Received also have their own methods.

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Perhaps later you can get a refund using that receipt.

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Perhaps you can.

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Deduct.

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Taxes using that through if you.

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Or self-employed or so on.

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And we have the same things for.

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Objects in Python in a program, so at least have an append method.

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Have a pop method, etc..

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Streams also have their own methods.

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Dictionaries also have their own methods.

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So the function, for example, if we see.

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In Maine, that pie, if we see this, get to this function, this function.

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When we call it gives us the list and then we store the list in these two twos variable.

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No variables in the real world could be just the plate.

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Where you place that instance, that object instance.

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So the plate would replace that coffee cup.

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That could be the variable.

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The received can also be placed in a small plate.

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Sometimes objects are not placed in plates, as you see.

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For example, ADD here is not associated with any variable.

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So variables can be optional.

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Sometimes you need them, sometimes you don't need them.

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So once we get that list, that list instance is returned from this function, and then we can use that

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returned object in other parts of the code.

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Similarly with this coffee.

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In here.

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So once this older coffee function gives us the coffee cup, then we can drink it.

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We can sweeten it by adding sugar to it and so on.

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So the older coffee is the process which makes that object instance.

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Now the big question is who designs these glasses?

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Who designs a list?

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Who designs a dictionary?

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Can you design a new class?

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So, a blueprint.

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Well, we can ask the same question in the real world.

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Who designed the coffee?

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Who designed the received?

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Can you design a coffee or a new object?

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Can you design something new?

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Some blueprints, which other people can use than to make instances of it?

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Of course, in the real world you can do it.

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It's not easy, but you can do it.

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And the same exact answer.

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Is given for the program.

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So you can actually design new classes and then use those classes to create instances, different instances.

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But when why would you design a class?

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Well, let's say that you want to create.

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A graphical user interface with buttons and text boxes.

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So in that case, you first would have to design a class a blueprint.

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Define the methods in that blueprint and then use that class to create actual windows.

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And you do the same for buttons.

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You would write a class for a button and then have that class create buttons.

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But there are two things you should know about designing a new class.

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First is that.

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Most of the time these classes have been designed by other programmers, so all they have to do is just

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use them to create instances.

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So just like we had the case with lists and dictionaries and strings, these are already designed.

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We can just.

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Create instances of them.

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However, I'm going to cover how to create classes later in the course, and we're going to go a lot

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in depth.

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So basically you are going to be the God of your program.

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So you're going to design.

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Objects, and then you're going to create object instances from your blueprints, from your classes.

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So those are the two things I wanted to tell you that most of the time other people have designed these

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things, classes and the second words that you're going to learn how to design them in the course later

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on.

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Therefore, classes still remain a mystery for now, and that's completely fine.

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Methods also remain a mystery for you, so you know how.

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Function blueprints look like.

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But you still don't know how class blueprints and method blueprints look like.

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So so far we have used functions as we did here with get to do parentheses.

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So that's how you you use that function.

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Then we also saw methods such as the append methods you use.

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It's here, but you still haven't seen how these methods are.

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From the inside.

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The blueprint of a methods.

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So the key concept to take from this video was the distinction between.

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Classes or types, in other words, and the instances that these classes create.

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If you understand that difference in your mind, then you are in good tracks.

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So that was about the anatomy of Python.

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Thanks a lot.

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And let's do some more videos.

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See you.