function Get-NestedGroupMembership {
   if ($args.count -eq 0) {
      break
   }
   if (test-path variable:GROUPS) {
      remove-variable GROUPS
   }
   $GROUPS=new-object system.collections.generic.list[string]
   function Get-NestedGroupMembership_Worker {
      if ($args.count -eq 0) {
         break
      }
      $P=$args[0].tostring()
      if ((get-adobject -filter { name -eq $P }).objectclass -eq "user") {
         try {
            get-adprincipalgroupmembership $P | % {
               get-nestedgroupmembership_worker $_.name
            }
         } catch {
            [void]'foo'
         }
      } elseif ((get-adobject -filter { name -eq $P }).objectclass -eq "group") {
         if (-not ($GROUPS.contains($P))) {
            $GROUPS.add($P)
            try {
               get-adprincipalgroupmembership $P | % {
                  get-nestedgroupmembership_worker $_.name
               }
            } catch {
               [void]'foo'
            }
         }
      }
   }
   $P=$args[0].tostring()
   get-nestedgroupmembership_worker $P
   write-output $GROUPS | sort-object
#   remove-variable GROUPS
}