Some PEP 505 fixes from Mark.

pep-0505.txt

@@ -48,7 +48,7 @@ work in Python::
     >>> title ?? 'Default Title'
     'My Title'
     >>> title = None
-    >>> title ?? 'Bar'
+    >>> title ?? 'Default Title'
     'Default Title'
 
 Similar behavior can be achieved with the ``or`` operator, but ``or`` checks
@@ -114,11 +114,11 @@ The ``None`` coalescing operator also has a corresponding assignment shortcut.
 
 ::
 
-    data ??= []
-    files ??= []
-    headers ??= {}
-    params ??= {}
-    hooks ??= {}
+    data ?= []
+    files ?= []
+    headers ?= {}
+    params ?= {}
+    hooks ?= {}
 
 The ``None`` coalescing operator is left-associative, which allows for easy
 chaining::
@@ -127,7 +127,7 @@ chaining::
     >>> local_default_title = None
     >>> global_default_title = 'Global Default Title'
     >>> title = user_title ?? local_default_title ?? global_default_title
-    'My Title'
+    'Global Default Title'
 
 The direction of associativity is important because the ``None`` coalesing
 operator short circuits: if its left operand is non-null, then the right