Escape in php to stop throwing 'undefined index/var' notice while using var directly

dave_escape.php

<?php
function _e(&$a,$return=NULL){
    return isset($a) ? $a : $return;
}

// usages

# scenario #1
$field = _e($_GET['field']);
# if field is not set, it will be set to null


# scenario #2
$field = _e($_GET['field'],'id);
# if field is not set, it will set to 'id'
# saving two lines of if code :)

_e function expects first arg as 'reference', so it wont throw notice :)