``__spam`` (at least two leading underscores, at most one trailing underscore)
is textually replaced with ``_classname__spam``, where ``classname`` is the
current class name with leading underscore(s) stripped. This mangling is done
-without regard to the syntactic position of the identifier, so it can be used to
-define class-private instance and class variables, methods, variables stored in
-globals, and even variables stored in instances. Truncation may occur when the
-mangled name would be longer than 255 characters. Outside classes, or when the
-class name consists of only underscores, no mangling occurs.
+without regard to the syntactic position of the identifier, as long as it
+occurs within the definition of a class.
Note that the mangling rules are designed mostly to avoid accidents; it still is
possible to access or modify a variable that is considered private. This can