9.5/_global_debug_functions_8php_source.html

<?php

// Short-hand debug function

// If you wish to use the debug()-function, and it does not output something,

// please edit the IP mask in TYPO3_CONF_VARS

function ‪debug($variable = '', $title = null, $group = null)

{

    if (!\‪TYPO3\CMS\Core\Utility\GeneralUtility::cmpIP(

        \‪TYPO3\CMS\Core\Utility\GeneralUtility::getIndpEnv('REMOTE_ADDR'),

        ‪$GLOBALS['TYPO3_CONF_VARS']['SYS']['devIPmask']

    )

    ) {

        return;

    }

    ‪\TYPO3\CMS\Core\Utility\DebugUtility::debug($variable, $title, $group);

}