Fix typo in assertSequenceEqual docstring.
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index 2ebf2da..db51e6d 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -505,7 +505,7 @@
     def assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None):
         """An equality assertion for ordered sequences (like lists and tuples).
 
-        For the purposes of this function, a valid orderd sequence type is one
+        For the purposes of this function, a valid ordered sequence type is one
         which can be indexed, has a length, and has an equality operator.
 
         Args: