add missing code

main.py

@@ -1,3 +1,4 @@
+import itertools
 import os
 import re
 from enum import Enum
@@ -31,6 +32,13 @@ SERVICES = {
     'soundcloud.com': MusicSource.SOUNDCLOUD
 }
 
+def _split_seq(iterable, size):
+    it = iter(iterable)
+    item = list(itertools.islice(it, size))
+    while item:
+        yield item
+        item = list(itertools.islice(it, size))
+
 def echo(link):
     o = urlparse(link)