What are the limitations of cStringIO.StringIO() ?

[ryles]

This reminds me. Would anyone object to adding a sentence to
http://docs.python.org/library/stringio.html#module-cStringIO just to
mention that attributes cannot be added to a cStringIO, like such:

% import cStringIO, StringIO
% StringIO.StringIO().value = 1
% cStringIO.StringIO().value = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'cStringIO.StringO' object has no attribute 'value'