Echo out a step in your debugging trace to find out where your code is executed

debug_step.php

<?php 

function debug_step($message = '')
{
    if (isset($_GET['debug'])) {
        /**
         * Count how many times the debug step has been called
         * @var integer
         */
        static $i = 1;

        echo sprintf("<strong>%d:</strong> (%s) %s <br>", $i++, debug_backtrace()[1]['function'], $message);
    }
}