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In this video, we'll look at the few rules
that we have to observe, when we use var positional

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parameters such as star effects
in our colour_print function.

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I'll start with that parameter entry in the
glossary - the one we looked at earlier:
https://docs.python.org/3/glossary.html#term-parameter

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I'm going to switch to a slide, because we
won't be talking about positional-only parameters.

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They're quite advanced - you'd only need to
use them if you were documenting functions

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that are implemented in C, for example.

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There are 5 different kinds
of parameters that you can use.

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As I said, we won't be looking at
positional-only parameters in this course.

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The description's blanked out in
the slide, to keep things simple.

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When we use the different parameter types
in our functions, we have to use them in the

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order that they appear below:

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Any positional-or-keyword arguments that we
define, MUST come first in the parameter list.

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If we have a var-positional parameter - that's
a parameter that starts with * - then it must

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come after any positional-or-keyword arguments.

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There's a good reason for that,
as we'll see soon.

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Any parameters defined after a var-positional
parameter must be keyword-only arguments (which

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includes var-keyword arguments).

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Finally, any var-keyword
arguments appear last.

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We'll be looking at how to define
var-keyword arguments later.

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We need to learn about dictionaries first.

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To understand why the ordering is important,
let's consider these rather strange, grey aliens.

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They're a very literal species - their brains
are a bit like computers, in that respect.

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Here, an adult alien is giving an
instruction to one of the children.

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Unfortunately ...

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... the instructions are ambiguous.

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The small alien had been told to hurry, and did
the best that it could, with those instructions.

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If we write ambiguous instructions in our
code, the best we can hope for is an error.

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The worst we can hope for,
is that our shoes get eaten!

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In the next video, we'll see how our code
would be ambiguous, if we don't define our

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parameters in the order I described.