Currently, there is no explicit example of how to do that, but there are examples of how to use squid-py, e.g. from IPython running in a Jupyter notebook.
See the Tutorials section.
You could even write an entirely server-side marketplace with a command-line interface, but let's not get carried away.
Note: There's also a squid-java library but it's currently not as full-featured as squid-js and squid-py.
## Aquarius
Aquarius is an application used by Marketplaces to store, update, read and delete metadata about assets. The Squid libraries all know how to talk to Aquarius, so you don't need to think about it or its API too much. You just need to make sure you have Aquarius running on a server somewhere.