creating pipelines in python

[per]

hi all,

i am looking for a python package to make it easier to create a
"pipeline" of scripts (all in python). what i do right now is have a
set of scripts that produce certain files as output, and i simply have
a "master" script that checks at each stage whether the output of the
previous script exists, using functions from the os module. this has
several flaws and i am sure someone has thought of nice abstractions
for making these kind of wrappers easier to write.

does anyone have any recommendations for python packages that can do
this?

thanks.