Resolving a PHP Notice Error

I am wanting to establish a default sort by preference when the user hasn’t specified one.  I setup to test this with:

<?php

if ( !is_set( $sort_by_preference ) ) {

    $sort_by_preference = "government_wording";

}

?>

But I am receiving a Notice error:

Notice:  Undefined variable: sort_by_preference in GIFI_codes.php on line 11- Line 11 is “if ( !is_set( $sort_by_preference ) ) {“What is the correct way to test this without triggering a Notice error?Ron
Ron Piggott



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