All language subtitles for 5. Print or Return

Something to point out is that when your function doesn't have a return statement, save, execute.
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it implicitly returns a None object.
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None is a specific object in Python which means nothing.
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It's not an integer.
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It's not a float.
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It's not a string.
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It's just None, it means nothing.
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So Python what it does is if it doesn't find the return statement on the background it does this:
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return None.
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So if you execute that, ups an indentation error.
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That's a good thing.
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So you see that all this block here has to be the same level of indentation, if indented four lines here,
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you have to indent for lines in here too.
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So indentation has to be consistent.
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That looks all right.
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So we got the same outputs, None here and None there.
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Some people do this mistake instead of returning, they do...
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They use print instead of using return they use a print function.
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The mean which works half the way.
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So it still returns the value.
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And it also returns None.
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So what's going on here is that when you call the function here Python will execute all these lines
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so it calculates the mean.
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Then it goes to the next line so line by line it will print the mean.
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So it will print out the mean in here and then it will look for a return statement.
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It doesn't find it so it will return None.
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The problem with this is that if you try to do some other operations with your mean value let's say
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my mean is equal to the mean function 0, 3, and 4.
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OK.
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And I want to print out my mean plus 10.
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So I would expect that this would give me the value of 7 is the sum divided by 3.
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So two point something plus ten, twelve point something,
but let's see what this will give me.
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So this will give me a type error instead.
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It's tried to add the None type which is None.
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So this is a None type.
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That's the type of this value. It's trying to add that to 10.
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So my mean is None because it's returns None, and the interpreter will try to add up
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that to 10.
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That's not possible.
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So that's why you shouldn't use print.
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If I replace that with return instead, remove the parentheses, save, execute, that will give me
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12.3.
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That is the average plus 10.
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However this doesn't mean you can not use print in your functions.
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You can actually do that.
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Let's say you just wants to print some information.
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Started, functions started and execute that.
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So you get the output of print in here, and then Python returns the mean, so you get the mean,
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you store it in here, the output
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of your function, but the value of the function is always what's you return in here.
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So if you see that.
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So always use return in your functions unless you have a very special reason to do so.