Cacher is the code snippet organizer for pro developers

for other user related stuff read: 

http://www.shawnwilkerson.com/modx-revolution/2012/03/10/programmatically-working-with-the-moduser-object/

<?php
/*
Check is a user is member of a certain group.
[[is_Member?groupname=`Gewerbekunden`]]
*/

if ($modx->user->isMember($groupname) ) {
  return 1;
} else {
  return 0;
}