bpo-36766: Typos in docs and code comments (GH-13116)

diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 9fe32eb..af0047f 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -3483,7 +3483,7 @@
                     self.assertEqual(got, expected)
 
         # However, if they're different members, uctoffset is not ignored.
-        # Note that a time can't actually have an operand-depedent offset,
+        # Note that a time can't actually have an operand-dependent offset,
         # though (and time.utcoffset() passes None to tzinfo.utcoffset()),
         # so skip this test for time.
         if cls is not time: