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# explain this function line by line

Can someone explain this function line by line please

```// This function receives a number as an argument.
// It returns the most popular flavors based on
// the number of likes, the most popular flavor
// first. (The number of flavors returned corresponds
// to the number in the argument.)

function get_flavors_by_likes(\$number) {

\$all = get_all_flavors();

\$total_flavors = count(\$all);
\$position = 0;

\$popular = \$all;
usort(\$popular, function(\$a, \$b) {
return \$b['likes'] - \$a['likes'];
});

return array_slice(\$popular, 0, \$number);

}

?>
```

I found usort pretty confusing. First comment on this page explains it fairly well. First variable stores the array by calling outside function. \$total_flavors and \$position don't even get used, they shouldn't be there. \$popular is also not needed, we could get rid of it and replace it's other uses in the code with \$all. We only need this

```function get_flavors_by_likes(\$number) {
//Define function, argument is how many flavors to display

\$all = get_all_flavors();
//Calls a previous function to assign \$flavors array to \$all

usort(\$all, function(\$a, \$b) {
return \$b['likes'] - \$a['likes'];
});
```

usort will compare each item in the array \$all, each time an item is compared to another they will be assigned \$a or \$b. If the function (\$b["likes"]-\$a["likes"]) returns a positive number, \$b will move 1 towards the top of the array, if negative it will move down and if 0 it will stay in that place. In this case when \$b is a larger number than \$a, it will be moved to the top of the array and we will have a descending list.

```    return array_slice(\$all, 0, \$number);
}
```

aray_slice displays from the array (\$all), starting at the first item in the array(0), however many items we asked for in the functions argument (\$number)*/