function groupExists( $group ) {
	global $wgGroupPermissions, $wgRevokePermissions,
		$wgAddGroups, $wgRemoveGroups,
		$wgGroupsAddToSelf, $wgGroupsRemoveFromSelf;
	return array_unique( array_merge(
		array_filter( $wgGroupPermissions[$group] ),
		array_filter( $wgRevokePermissions[$group] ),
		$wgAddGroups[$group], $wgRemoveGroups[$grop],
		$wgGroupsAddToSelf[$group], $wgGroupsRemoveFromSelf[$group]
	) );
}