xpathEscape() inputs and expected output

xpath_escape_test.php

<?php
    require('xpath_escape.php');
    $strings = array('i think therefore i am',
                     'the pimp\'s "main squeeze" was talkin\' jive');

    foreach($strings as $query)
        echo xpathEscape($query).PHP_EOL;

/**
* EXPECTED OUTPUT:
* "i think therefore i am"
* concat('the pimp',"'",'s ','"','main squeeze','"',' was talkin',"'",' jive')
*
* EXAMPLE USAGE
* $xml->xpath('//node[subnode='.xpathEscape($string).']');
* 
* NOTE: because if no single or double quotes are present the original query is returned
* wrapped in the delimeter (default " but you can pass it in as an optional argument
* to xpathEscape()) you do not include string delimeters in the xpath expression when
* calling the escape function
*/