Python toplevel in a Web page

[Franck Ditter]

Hello,
I wonder if I can find some source code example
of a Python 3 toplevel box in a Web page.
Something simple, no mySQL, no Django hammer, etc.
Just the basics of the technology to get the
content of a small text editor in which the user
writes some Python script, to be analyzed (eval'ed)
then whose result is to be written in another text box.
Simple, pythonistic.
Thanks for the pointer,

    franck