Environment:

* Python 3
* IPython 3.2

Every time I shut down a IPython notebook and re-open it, I have to re-run all the cells. But some cells involve intensive computation.

By contrast, `knitr` in R save the results in a cache directory by default so only new code and new settings would invoke computation.

I looked at `ipycache` but it seems to cache a cell instead of the notebook. Is there a counterpart of cache of `knitr` in IPython?