1. I introduced the "Sage preparser", which does things like replacing "1/3" by "Integer(1)/Integer(3)" in Sage, before feeding that input to Python to be evaluated; Robert Bradshaw also did a lot of work on the preparer. The preparser uses a hook into the IPython evaluation system. I decided I really needed Sage to use a preparser like this during a talk I gave at Pycon 2005, based on audience feedback, which is why it exists.

2. I would really like somebody to remove the preparse code from Sage and make it a standalone library available on pypi. Here's the code (happy to relicense it under BSD): https://github.com/sagemath/sage/blob/master/src/sage/repl/p...

3. Permalink to your example -- http://sagecell.sagemath.org/?q=nwzdzn