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so in the previous we started
talking about functions and i ended it

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by saying that we could add the
functionality to our center

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text function and to do the
same as the example on line 22 with

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the 5 parameters that variable number of
parameters that are pass currently to the

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print function what we can do the way we
can do that is we can use the star

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talked about for arguments and then
iterate through the argument list and

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concatenate all the arguments into one string
before centering it so what we need to is

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make a change here we need to use the
Asterix and if you remembered by looking at

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the built-ins doc string for print we
knew that by adding an asterix that

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signifies Python their is as a variable
number of parameters so then what you need to do is

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we can't just put string equals text because we can now have multiple parameters

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so what we need to do is start off
by making an empty string and we need to

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create a for loop and actually add our
parameters so put.....

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and args we are gonna change this up here to be the
parameters so in this case the arguments and put.....

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...and once we do that of course

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the indents back on line 12 to the code
we're going to have a text variable

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which contains all the arguments and it
should work quite nicely without any

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code modification
in terms of calling the codes so if we run this we should find

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that it still works still works as it is
with one parameter but if we then changed

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this....and we do something like...

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...so we've got 5 paramteres and we've

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got a numbers and strings
we can use their so if we run that you will find in the

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last line first second 3 4 spam so it quite happily
accepted the arguments and centered them

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as you can see on the screen their now I have
said previously that concatenate strings

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in a list is not very efficient and
there is a more efficient way of doing

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this using list comprehensions but
we're not really at that point at the

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moment we're going to cover those later
in the course so we are not going to use one here

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just something to keep in mind that it
isn't the most efficient way

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currently of concatenating strings and
you might think ok maybe we can

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use the join here we can do something like....

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so you might think we can go........but if you run that we get an error

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and of course the error is that the join method only
works with strings and we want to allow

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numbers as well and that's why we are getting the error their so that's why we can't use join and

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if you change that to make a join then
make...and run that

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you can see that clearly wasn't the result of what we
were trying to to do their so what we're

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doing is undo those changes and stick
to what we originally coded running that you can see it is

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working again but again to keep in the
back in mind that this isn't the most

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efficient way of doing things and later
in the course we're looking at list

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comprehension method to make this a
little bit easier how you go about fixing it now the print function

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if you go back to that again so I just
closed the window down so again that is control clicking if your on a

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Windows machine or Linux machine and on MAC it is command click

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go back to the definition again you can see there's
also 3 named parameters this are also called

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default parameter values you can see the
names the first one sep that is a string

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that's going default to a space if we
don't provide a value and end is also a

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string the defaults to new line we have
talked about that before but the final

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2 named parameters also add a printing to
our file with an option to flush the file

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buffer so the data is written immediately at this point you're
probably wondering why flush appears in

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the doc string but is missing in the
actual function definition you can see

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how it is actually missing their so I'm wonder that as well and I don't have answer at the moment and Guido van Rossum who

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is the creator of Python was involved
in a discussion about this in January

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2016 so we'll see what Python developers
come up with it may be fixed by the time

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you view this video and in any
event so what we can do now is we can

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make our center_text function behave
in the same way as print

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by declaring the same named parameters
then passing most of the arguments strait to

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the print function which is pretty cool so lets close this down and make a change to our

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center text we're gonna leave arguments their but we are gonna add these extra named parameters this named arguments again

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which are also known as the default parameter values so we're going to start with

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.......

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......

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...so we added those named arguments now as you can see and what we can now do is come down here and add a print on line 13 and add this on

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the end so we can put....

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....and noting when you type flush you can see that IntelliJ is

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telling you this is a parameters its actually showing you so it's quite interesting when you

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do you actually look at the way IntelliJ
shows you a variable it actually does try

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and point out where things are
parameters whether it's just a local

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variables so on and so forth so for
example if we go back here we got v for variable as you can see

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that's pretty cool ok so....now because we can concatenating the values to print we don't pass

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sep on to the print function but
instead we used in the separator and I'm gonna do that

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on line 11 so instead of putting a space their we are gonna put + sep...so whatever is

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passed as a separator is going to be
added their and you can see the default if you don't

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specify a named argument is going to be a
space and all the other named

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parameters or named arguments I've just provided
to print when we called it so test this

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first by using a different separator when
we go to call the code on line 22 so

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let's do that so we gonna put....and try running that and you can see that

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instead of using spaces to separate our
arguments we've now got a colon so

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it's working perfectly

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although there is one problem you may have notice and that's
the colon right at the end of the string

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we could write a code to strip it off
and this is gonna be the final versions

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centered text now we would do that but we are gonna be using this function we cover list

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comprehensions later in the course and
that will also cure that particular

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problems so if you wanna have a go at
removing the trailing color right on the end

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using the techniques we've covered so far in
the course by all means do that but we are not

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actually do that here now if the code
on line 13 if that code

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end=end and file=file looks a little bit odd don't worry can

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take a bit of used to and if you've used other programming languages you might be

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wondering about things like variable scope
and try to work and how Python is

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resolving the differences between the
two ends but try to understand that in terms of

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scope doesn't really work so an easier way
to look at it might be think of the

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parameter declaration end=/end which is defined on line 8 as doing 2 jobs

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so it specifies a parameter called end but it also changes the way the function

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is called so that whenever end= appears in the function call whatever

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follows the equal is assigned to the
parameter end that it created so

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within the center_text there is also a
variable called end that has a value / end

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unless another value was specified when
center_text was called so essentially when line 13

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is executed end= is sort of
interpreted as an instruction to take

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whatever comes next and use that value
to initialize one of the prints

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parameters that also happens to be the
end but that only exists within print

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if that makes sense and again what you can do here just to confirm if start typing

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it's always a good thing just to look at
the little color coding circle to the

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left hand side

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IntelliJ is usually got your back there
and that's clearly telling you that

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P is a perimeter and if you started typing
texts as you can see

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we got a different code we got a V for variable so they are very handy to have that

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color-coded so that if your just wondering why a
particular value and obviously we're

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talking about end so the same applies to end as
well e you can see that is parameter of end so the only reason

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we've actually used the names end file and flush that we defined on line 8

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was to make the function
compatible with print os if you change

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the definition it might make it easy to see what's
going on so gonna do that two stages

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first let's go back to the definition
on line 8 lets changes to instead of being end

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will put.....

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and for file....and for flush lets put....so now we have change the

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names you can see there now on line

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13 IntelliJ is really helpfully
highlighted the errors and as such you can really

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easily see which bits of the call to
print a which so the first bit is still

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the named arguments that's part of the print
function and the second part is

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obviously the variable name where it is gonna get that value whatever the value is suppose to contain and if you hover over their we

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can see it says unresolved reference end
and we can change that then once we do

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that any ambiguities removed so we
type....

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......

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the errors have gone away we should be up to
run this and it's working well and again

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if you were in any doubt you can hover over when
there's an error to see what the error

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was which I showed you just before I made the changes so now that that's done we have remove any ambiguity but at the expense

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of center_text now having a different
signature to prints so obviously print had those

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names end file and flush but in
our case the center_text functions

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is using

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end_char centered_text and flush_me so its got a different

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signature to prints so you actually hear
that term signature by the way is a way

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of referring to a set of parameters in a
function definitions so two functions

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that take exactly the same parameters
are said to have the same signature

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so hopefully it is now clear which variables are
being used and how we gave them

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different names and that's hopefully remove
that early confusion so it would still be

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better to use the same names as print
though because they will be the names that

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users of a functional likely be used to
if they see a special print function because presumably

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that will be pretty used to standard printo
function that comes with Python

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but if you find that confusing then of course you can
call your parameters whatever you like

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and you saw as change that in this video so what I'm gonna do is put them back to what they

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were so that call to center_text is looks the same
as to print

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so I'm going to rename this so what I'm gonna do is show you how to do a refactor so I'm gonna select the parameter and right click it and go refactor rename and change to end and press Refactor or press enter you can see how that has

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changed there and its also changed down here this can
be a good way if your renaming variables

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to take the features
of IntelliJ to do it for you and they will change

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all references to that wherever it's
been used in your

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program so likewise for this one we change centered_file to just file press enter and change

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and likewise the third one
flush and I can come down here if I wanted to

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instead refactor rename it still
IntelliJ is smart enough to know its a parameter and if

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change that back to flush press enter its correctly
change the parameters as well as the argument

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ok so I'm going to finish this video
here now when we come back we're going

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to continue on and what will do first is
change it so that the output goes to

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a file so see you in that next video