lua script for imapfilter that deletes empty mailboxes

cleanup.lua

--- Removes mailboxes with no messages and no subfolders.
--- Will keep iterating over folders with subfolders until it
--- cannot find anymore candidates to delete
--- called by running: `removeEmptyMailboxes(account, 'INBOX', '*')`
function removeEmptyMailboxes(account, base, pattern) 
   candidates = account:list_all(base,pattern)

   while(#candidates > 0) do
      print ("Start scanning " .. #candidates .. " boxes to see if empty...")
      candidates = removeMailboxes(account, candidates) 
   end
   
end

function removeMailboxes(account, boxes)
   candidates = {} -- folders we could not delete because it had sub folders
   deleted = 0
   for _,box in pairs(boxes) do
      exist, unread, unseen, uidnext = account[box]:check_status()
      if(exist==0) then
	 subboxes = account:list_all(box, '*')
	 if (# subboxes > 0) then 
	    print ("Can't delete " .. box .. " because it has " .. # subboxes .. " folders")
	    table.insert(candidates, box)
	 else
	    print ("Want to delete " .. box)
	    account:delete_mailbox(box)
	    deleted = deleted + 1
	 end
      end
   end

   if(deleted>0) then
      return candidates
   else
      print ("Could not delete any mailboxes thus no more candidates to delete.")
      return {}
   end

end

Thank you. Had to call it like this removeEmptyMailboxes(account, '', '*')