Hide the Page list's heading

Having a really hard time learning how to hide the page list’s heading. I’m trying to learn by codex here.

I successfully got the child pages to appear and styled them. But I cannot get the argument to hide the title to work. I know I’m doing this wrong but I don’t understand the tutorial. Trying to hide the pages is either unsuccessful or breaks the site depending on how I enter the 2nd argument. What am I doing wrong? Should be a simple fix I imagine. I’m still learning the lingo as well so please don’t beat me up ??

<?php wp_list_pages('child_of=4', 'title_li' = __('')); ?>

Thanks a bunch!