Backport PEP 3141 from the py3k branch to the trunk. This includes r50877 (just
the complex_pow part), r56649, r56652, r56715, r57296, r57302, r57359, r57361,
r57372, r57738, r57739, r58017, r58039, r58040, and r59390, and new
documentation. The only significant difference is that round(x) returns a float
to preserve backward-compatibility. See http://bugs.python.org/issue1689.
diff --git a/Misc/NEWS b/Misc/NEWS
index 608982e..6aad4d8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -346,6 +346,8 @@
 Library
 -------
 
+- Issue #1689: PEP 3141, numeric abstract base classes.
+
 - Tk issue #1851526: Return results from Python callbacks to Tcl as
   Tcl objects.