function subst(array &$old, $new)
{
if (is_string($new)) {
$new = [$new];
}
foreach ($new as $hdr) {
$old = preg_grep('/' . preg_quote(strstr($hdr, ':', TRUE), '/') . ':.+/', $old, PREG_GREP_INVERT);
array_push($old, $hdr);
}
}