The problem with overwriting the array rather than appending to it, is if we want to hook into UserIsBlockedFrom in another extension for any reason and that extension is included before Wall, the hook won't work as the array will be overridden here. Using ```$wgHooks['UserIsBlockedFrom'][] = 'WallHooksHelper::onUserIsBlockedFrom';``` should work fine, and it is standard MW way of adding hook calls. :)