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Hi.

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Welcome back.

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In this video, you will learn how to use dog strings.

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So what are those strings?

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Well, you have heard me mention them here and there.

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But we never explained exactly what they are.

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So you assume that when we do something like help.

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And you check the help.

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Documentation of a function such as input or prints or Len.

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Let's try, Len.

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You get this documentation.

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This is actually called the docstring of that function.

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So if you are on charm.

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You can actually see where this docstring is written.

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So in a python file just writes len and then right click over it and go to go to then to implementation.

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That will take you at the file where Len is written.

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Now this is a fake function, but the string is.

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The actual docstring.

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So this docstring is the one displayed in here as well.

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So when you do help lend, for example, then the help function generates these automatic text help

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on built in functional and in module bulletins, and it also generates the structure of the function

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and then it extracts the docstring from the place where the function is defined.

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In this case it is here.

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So we can do the same.

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For our own functions.

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So dog strings are written in the first line.

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And use triple quotes from both sides of the strings.

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So then you write the description of the function so that if your function is later used by someone

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else or by you, they can use the help function and see the help documentation, the docstring of the

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function.

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So what can you write here?

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Well, we can learn from these functions here.

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So the land function says that the return, the number of items in a container, that's what the land

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function does.

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So it calculates the number of items in the list or string or other sequence types of objects.

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And there are other functions as well.

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So that's the input function.

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This has more description and when there is more text you want to.

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Put the text between the triple quotes in separate lines, as you see here.

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In our case.

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So make a space and write something.

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Reads a text file and return the list of.

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So since this is getting too long, I think we can split it and we can write the neck the rest in here.

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So read the text file and returns the list of to do items.

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So that should do it.

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So it's the same format as this one here.

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How is this docstring useful now?

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Well, currently it is not very useful given the structure of of our program, but you'll see later

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on that you can create multiple Python files for one program and then these files can interact with

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each other.

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Then you might want to access the help documentation of a function from another file.

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And so then it becomes helpful to have this docstring as an experiment.

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You could also try the health function in here and say get to dos.

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And so you want to print out the output of help here in the command line in the python console.

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You don't have to use print, as I have mentioned before, for functions, for variables.

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You just call the variable or the function and you just get the output.

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But here you want to print the output of help.

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So let's run the script and that's what we get.

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So that's the request to enter it to do, which is executed by this line.

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So that's the output of that.

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But before this we get this docstring printed out by this help file.

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So that's the help documentation.

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As you see help and function get to do is module main.

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This is automatically generated by the help function and then we have a representation of the to dos

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function.

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So it shows what's file, what arguments it gets.

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It shows that this has a default value.

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And then it shows the docstring of the function in here.

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So read the text file and return to the list of To-Do items.

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So now if anybody else.

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Uses your function, they can read what the function does by using the help function.

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And the docstring you write is important.

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So let me close that.

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Delete that line.

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So that was one use case of the docstring when someone else uses your functions or you use your your

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functions through the help file.

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Another use is of course for you directly so when you write.

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And then then read your code.

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You look at your code later on and you see these functions.

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You can just look at the docstring, you can read what it does.

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So that will tell you what this function does so that you don't have to look at the code.

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So descriptions are good.

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Let's write a f string for this function as well.

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So three double quotes a space.

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Right to do item list in the text file.

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So that should be enough.

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That's a bold docstring.

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So it is.

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It is recommended to use docstring for every function.

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Some people just don't use them, especially when you have simple very simple functions.

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But the general recommendation is to use doc strings.

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So thanks a lot for following this.

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I hope it makes sense and see you later.