Issue #27076: Doc, comment and test function name spelling fixes
Most fixes to Doc/ and Lib/ directories by Ville Skyttä.
diff --git a/Lib/wsgiref/headers.py b/Lib/wsgiref/headers.py
index 6c8c60c..5a95e84 100644
--- a/Lib/wsgiref/headers.py
+++ b/Lib/wsgiref/headers.py
@@ -59,7 +59,7 @@
Return None if the header is missing instead of raising an exception.
Note that if the header appeared multiple times, the first exactly which
- occurrance gets returned is undefined. Use getall() to get all
+ occurrence gets returned is undefined. Use getall() to get all
the values matching a header field name.
"""
return self.get(name)