This is a continuance of Part 1.
Omitting Mandatory Parameters
Some parameters are mandatory, and some aren't. This is something you have to consider when writing your own functions.
// calling function with 3 mandatory parameters
$get = getID( $username, $userlevel );
// third parameter is to return the ID with link to profile or not. It is omitted, and will produce an error. Parameters can be made optional, when creating the function.