PEP 227: remove placeholder comments. (python#561)

Author: Mariatta

pep-0227.txt

@@ -221,16 +221,12 @@ are unusual for lexically scoped languages; there is typically a
 mechanism to create name bindings (e.g. lambda and let in Scheme)
 and a mechanism to change the bindings (set! in Scheme).
 
-XXX Alex Martelli suggests comparison with Java, which does not
-allow name bindings to hide earlier bindings.
 
 Examples
 ========
 
 A few examples are included to illustrate the way the rules work.
 
-XXX Explain the examples
-
 ::
 
     >>> def make_adder(base):
@@ -289,8 +285,6 @@ The call to ``g()`` will refer to the variable i bound in ``f()`` by the for
 loop.  If ``g()`` is called before the loop is executed, a NameError will
 be raised.
 
-XXX need some counterexamples
-
 Backwards compatibility
 =======================
 
@@ -479,8 +473,6 @@ straightforward manner, they are preferred.
 Implementation
 ==============
 
-XXX Jeremy, is this still the case?
-
 The implementation for C Python uses flat closures [1]_.  Each def
 or lambda expression that is executed will create a closure if the
 body of the function or any contained function has free
@@ -504,8 +496,6 @@ that access an enclosing scope is returned, should not prevent
 unreferenced objects from being reclaimed by the garbage
 collector.
 
-XXX Much more to say here
-
 References
 ==========
 
@@ -517,7 +507,6 @@ References
 Copyright
 =========
 
-XXX
 
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