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Welcome back.

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In many places where the Python
interpreter is expecting a single value,

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but the code provides multiple
expressions separated by commas it

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automatically packs all those
values into a single tuple.

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This is just a convenience that
makes the code look a little nicer.

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It looks like you are working
with multiple values,

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when really is just making
one tuple out of them.

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For example, in this code we have several
pieces of the information about an actor

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Julie Roberts and
a movie she was in Duplicity.

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We can explicit make those different
pieces of information into a tuple

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using parenthesis like
we do on line number 1.

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So, we have open parenthesis there,
closed parenthesis,

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this is our usual way of creating a tuple.

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In between we have a bunch of values
there's Julia, Roberts, 1967.

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All of these values are separated by
commas to indicate where one expression

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ends and another begins.

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So that's the syntax that you've
already seen for creating tuples.

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It turns out that line 3
does exactly the same thing.

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It's exactly the same except that
we've left out the parentheses.

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No more parentheses here and
it implicitly reads that as,

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we got a bunch of values,
we gotta pack it into a tuple.

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On line 4 you can see as with any tuple,
Julia is the name of the variable.

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We look up its value, its value is
a tuple, square bracket 4 says,

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go and get the fifth item,
so Julia is 1, 2, 3, 4, 5.

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So what it prints out here should be 2009.

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So lines 1 and
line 3 are just synonyms for each other.

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Line 3 is just a way that maybe
looks a little bit better as if

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you have multiple values.

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One place where this is especially useful
is when a function wants to return

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multiple values.

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For example, in this code,
circleInfo is a function

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and it wants to return two values.

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The circumference of the circle,
and the area of the circle.

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You can only return one value
from a Python function, but

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that value can be a tuple
as we've done here.

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So that works fine, I can print the circle
information of a circle with radius 10.

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And it has a circumference of 62.83,

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and an area of 314 But

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I also have the option, if I think it
looks better to leave the parenthesis out.

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And it will automatically return a tuple,
and

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I'll get exactly the same output,
there you go.

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So that's tuple packing,
we'll see you next time for unpacking.