‫There is a unique thing that we can do with functions that we haven't seen before, and they're called
‫doc strings.
‫Let me show you what I mean.
‫If I had a function here and we'll just call it test and test, let's say receives a parameter that
‫is a and in here it's going to print a what?
‫A useless.
‫Completely useless.
‫Function.
‫Now, if I run this well, nothing's going to happen because I have to call test and then say, well,
‫exclamation marks.
‫And you see that our function works.
‫But we can actually with functions in Python use something called doc strings and it looks something
‫like this.
‫You do single code, single code, single code.
‫So three of them.
‫And then at the bottom once again, single code, single code, single code.
‫So the beginning of the function like this and in here I can add some info about the function.
‫For example, this function tests and prints.
‫Per am a.
‫Now, here's the interesting part.
‫If I run tests here and I do brackets, look at that.
‫My editor tells me info.
‫This function tests and prints per am a this is called a doc string.
‫And what it allows us to do is to actually comment inside of our functions in a way that if another
‫person, let's say, is using the test function, they can actually let say in the future, when we
‫write large applications where it's not just ten lines of code or maybe we have different files instead
‫of just finding what test does.
‫As I'm typing it, it's going to tell me, hey, test is going to return or print param a so I find
‫out information about this and if we ever use something like length, for example, and run this, you
‫see that this gives us information about the function by using doc strings, but it comes built in with
‫Python.
‫Another way to view this.
‫Mind you, when we talk about devolve payer environments, our editors are going to do this automatically.
‫But there's a few other ways that we can actually read this.
‫For example, I can do the help function, which we haven't seen before, which comes prebuilt with
‫Python.
‫And we don't want to call the function.
‫I just want to call help on test if I run this.
‫Look at that.
‫I get test info.
‫This function tests and prints parameters so we can use help to find out what a function does, which
‫is really, really useful.
‫One other way to do this is to use what we call a magic method or a dunder method, which again we'll
‫get into later on in the course.
‫I do double underscore then.
‫I do, doc.
‫And then double underscore like this if I click run.
‫Well, we have to print something here, so let's print.
‫Click Run and look at that.
‫I get the same thing.
‫So these dog strings are really, really useful to add comments and definitions to your functions so
‫that when other people on your, let's say, team or coworkers come across your function that you created,
‫they're able to understand what it does right away without searching through your python files or multiple
‫files.
‫Very useful feature.