Suggest using default values for __init__ arguments to make classes
unpicklable.
diff --git a/Doc/lib/libpickle.tex b/Doc/lib/libpickle.tex
index 579992f..128b29d 100644
--- a/Doc/lib/libpickle.tex
+++ b/Doc/lib/libpickle.tex
@@ -86,7 +86,9 @@
\renewcommand{\indexsubitem}{(pickle protocol)}
Next, it must normally be possible to create class instances by
-calling the class without arguments. If this is undesirable, the
+calling the class without arguments. Usually, this is best
+accomplished by providing default values for all arguments to its
+\code{__init__} method (if it has one). If this is undesirable, the
class can define a method \code{__getinitargs__()}, which should
return a {\em tuple} containing the arguments to be passed to the
class constructor (\code{__init__()}).