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Functions allow us to reuse bits of code. For example, say that we are calculating tax on transactions. We can wrap up our code in a functional unit and give it a name:
function calculate_tax($price, $tax) {
    $sales_tax = $price *$tax;
    $total = $price + $sales_ tax;
    return $total;



From then on we can just call that name and pass it some information (called arguments):

calculate_tax("53", "0.075")

This will save us time as well as make our code easier to review. Lets take a look at some more in-depth learning resources.

Recursion Function

Taken from

function recursion($a)
    if (
$a 20) {
recursion($a 1);