To increase the purity of the pythons, put them in a container with cabbage leaves (not heads) next to them and check them after some time. The python eats only the leaves above, below, right and left. I use baskets, place the python in the middle and put leaves around. ALWAYS use higher purity plants.
You can read info here:
http://www.salem-wiki.com/mediawiki/ind ... orm_Python