newbie question about PYTHONPATH

[Tim Hanson]

I am to the point in _Learning_Python_  where functions are introduced.

I decided to experiment by putting a function into  a file and importing it 
into Idle.  Of course, Idle couldn't find it, so I executed the following 
command in Bash:

PYTHONPATH=/home/foo/prog/learning_python
export PYTHONPATH
env | grep PYTHONPATH

~$PYTHONPATH=/home/foo/prog/learning_python

Idle still won't find it.  I'm doing something wrong?