Richard Stanton <stanton@haas.berkeley.edu> wrote:
> I'm trying to use the :session option so I can import modules, etc.,
> just once at the beginning of my document, like with am IPython
> notebook. Unfortunately, the output from these code blocks contains
> some extraneous characters. For example:
>
> #+BEGIN_SRC python :session :results output
> a = 2
> b = 3
> c = 4
> print 'a=      ', a
> print 'b =     ', b
> print 'a + b = ', a+b
> #+END_SRC
>
> #+RESULTS:
> :
> : >>> >>> a=       2
> : b =      3
> : a + b =  5

I also see this behavior.  I asked the list some time ago [1], but I
didn't follow up beyond the initial email.

> How can I stop the production of all those ">" signs (sometimes
> they're dots), which don't appear if I run the same code block without
> the :session option?

I've attached a patch that seems to fix the example you gave and the
cases from my earlier email.  I don't know enough about babel's
internals to know if it is a good way to fix it, but at least it might
serve as a quick fix for you until there is a better solution.

[1] http://thread.gmane.org/gmane.emacs.orgmode/79014