remove obsolete names and consistently quote strings (#1343)

pep-0616.rst

@@ -88,7 +88,7 @@ may use the constant-time behavior of comparing the lengths of
 the original and new strings::
 
     >>> string = 'Python String Input'
-    >>> new_string = string.removeprefix("Py")
+    >>> new_string = string.removeprefix('Py')
     >>> modified = (len(string) != len(new_string))
     >>> modified
     True
@@ -235,7 +235,7 @@ from the proposed behavior via by the following::
 
     >>> s = 'Foo' * 100 + 'Bar'
     >>> prefix = 'Foo'
-    >>> while len(s) != len(s := s.cutprefix(prefix)): pass
+    >>> while len(s) != len(s := s.removeprefix(prefix)): pass
     >>> s
     'Bar'
 
@@ -243,7 +243,7 @@ or the more obvious and readable alternative::
 
     >>> s = 'Foo' * 100 + 'Bar'
     >>> prefix = 'Foo'
-    >>> while s.startswith(prefix): s = s.cutprefix(prefix)
+    >>> while s.startswith(prefix): s = s.removeprefix(prefix)
     >>> s
     'Bar'