fix streams.get_by_itag function. (#288)

pytube/query.py

@@ -187,7 +187,7 @@ class StreamQuery:
     def get_by_itag(self, itag):
         """Get the corresponding :class:`Stream <Stream>` for a given itag.
 
-        :param str itag:
+        :param str int itag:
             YouTube format identifier code.
         :rtype: :class:`Stream <Stream>` or None
         :returns:
@@ -196,7 +196,7 @@ class StreamQuery:
 
         """
         try:
-            return self.itag_index[itag]
+            return self.itag_index[int(itag)]
         except KeyError:
             pass
 

tests/test_query.py

@@ -111,6 +111,7 @@ def test_get_by_itag(cipher_signature):
     :class:`Stream <Stream>`.
     """
     assert cipher_signature.streams.get_by_itag(22).itag == '22'
+    assert cipher_signature.streams.get_by_itag('22').itag == '22'
 
 
 def test_get_by_non_existent_itag(cipher_signature):