piping with subprocess

[Rick Dooling]

I spent half a day trying to convert this bash script (on Mac)

textutil -convert html $1 -stdout | pandoc -f html -t markdown -o $2

into Python using subprocess pipes.

It works if I save the above into a shell script called convert.sh and then do

subprocess.check_call(["convert.sh", file, markdown_file]) 

where file and markdown_file are variables.

But otherwise my piping attempts fail.

Could someone show me how to pipe in subprocess. Yes, I've read the doc, especially

http://docs.python.org/2/library/subprocess.html#replacing-shell-pipeline

But I'm a feeble hobbyist, not a computer scientist.

Thanks

RD