From 0f72aa8f94f5b834af5c934a671449286ce5e2e1 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Sat, 3 Mar 2018 17:08:49 +0100
Subject: [PATCH] Fix set union

---
 telethon/sessions/memory.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/telethon/sessions/memory.py b/telethon/sessions/memory.py
index 42af7ad9..4d7e6778 100644
--- a/telethon/sessions/memory.py
+++ b/telethon/sessions/memory.py
@@ -125,7 +125,7 @@ class MemorySession(Session):
         return rows
 
     def process_entities(self, tlo):
-        self._entities += set(self._entities_to_rows(tlo))
+        self._entities |= set(self._entities_to_rows(tlo))
 
     def get_entity_rows_by_phone(self, phone):
         try: