There are several ways to convert, start notebook with –script flag will save .py file alongside .ipynb on every save. You can also (as ipynb is json), load it, loop through it and eval codecell in current namespace.
If you don’t want to output a Python script every time you save, or you don’t want to restart the IPython kernel:
On the command line, you can use nbconvert:
$ ipython nbconvert --to=python [YOUR_NOTEBOOK].ipynb
As a bit of a hack, you can even call the above command in an IPython notebook by pre-pending ! (used for any command line argument). Inside a notebook:
!ipython nbconvert --to=python config_template.ipynb