Continue going through the language reference, bringing it up-to-date.
In particular, document the new comprehensions and remove mentions of long integers.
Fix a bunch of related things in the lib ref.
diff --git a/Doc/library/constants.rst b/Doc/library/constants.rst
index c36b2fa..634656a 100644
--- a/Doc/library/constants.rst
+++ b/Doc/library/constants.rst
@@ -5,6 +5,11 @@
A small number of constants live in the built-in namespace. They are:
+.. note::
+
+ :data:`None`, :data:`False`, :data:`True` and :data:`__debug__` cannot be
+ reassigned, so they can be considered "true" constants.
+
.. XXX False, True, None are keywords too
.. data:: False
@@ -37,3 +42,10 @@
slicing syntax for user-defined container data types, as in ::
val = container[1:5, 7:10, ...]
+
+
+.. data:: __debug__
+
+ A boolean value that is :data:`True` if Python was not started with the
+ ``-O`` command line option. Its value is used indirectly by the
+ :keyword:`assert` statement, but it can also be used directly in code.