PHP and headers and... aye, it sucks

gistfile1.aw

<?php
// a function to check if a specific header exists, current way due to headers_list() returning numeric array
function header_exists($lookup)
{
    $headers = headers_list();
    foreach($headers as $header){
        if(0 !== stripos($header, $lookup)){ // or other lookup...
            continue;
        }else{
            return true;
        }
    }
    return false;
}

// what if the function would return headers in a key => value fashion?
function header_exists($lookup)
{
    return array_key_exists($lookup, headers_list());
}

// the thing is that, AFAIK, every single header follows the `Key: Value` pattern, why such a weird result?
?>