How to iterate over and extract selected parts of multipart message

[Greg Davidson]

It would seem that there would be a way to use GNU Mailutils to
examine the parts of a multipart email, as with the mmh command
    mhlist -file amsg.eml
and to extract selected parts with the Transfer-Encoding undone
as with the (unfortunately buggy) mmh command
   show -file amsg.eml -part 2

I have installed the package with Guile bindings thinking that might
be helpful.  Looking through the Mailutils documentation I am failing
to find out any way of approaching this problem with or without Guile.

I am imagining that I need to map or iterate over all messages in a
file (I use mh, so there's only going to be one) and then map or iterate
over the parts.  Maybe I'm thinking about this the wrong way?

I appreciate any assistance.  If I can get this to work I will write up
what I learn to hopefully assist others.