diff --git a/telethon/telegram_client.py b/telethon/telegram_client.py
index 812aa613..56619ec0 100644
--- a/telethon/telegram_client.py
+++ b/telethon/telegram_client.py
@@ -1,9 +1,9 @@
 import os
-import re
 from datetime import datetime, timedelta
 from functools import lru_cache
 from mimetypes import guess_type
-from pprint import pprint
+
+import re
 
 try:
     import socks
@@ -608,7 +608,7 @@ class TelegramClient(TelegramBareClient):
            some performance loss.
         """
         possible_names = []
-        if not isinstance(entity, TLObject) or type(entity).subclass_of_id in (
+        if not isinstance(entity, TLObject) or type(entity).SUBCLASS_OF_ID in (
                 0x2da17977, 0xc5af5d94, 0x1f4661b9, 0xd49a2697
         ):
             # Maybe it is an user or a chat? Or their full versions?