Good example of a working custom REST endpoint (but not an admin:* one)

I'm trying to piece things together from the restmap.conf docs, to get a working custom endpoint that I can use. Note that i do not want to use this with setup.xml and I just want a plain old endpoint that extends splunk.rest.BaseRestHandler, not an EAI endpoint.

http://www.splunk.com/base/Documentation/4.2.1/admin/restmapconf

Following what's written in restmap.conf I think I've done everything right and I've read through the doc a few times, but no luck.

I get a 500 response when I go to https://localhost:8089/services/my_path, saying "ImportError: No module named MyFileName" and I dont see how to debug or troubleshoot anything.

Here's my stanza in restmap.conf:

[script:random_unique_name_like_say_fred]
match = /my_path
handler = MyFileName.MyClassName
requireAuthentication = true

and in $SPLUNK_HOME/etc/apps/<app_name>/default/rest/MyFileName.py there is a class defined called MyClassName that extends splunk.rest.BaseRestHandler. And the python is pretty simple and running it manually it seems free of syntax errors.

Ideally if someone can point me to an app on Splunkbase that has successfully set up a non-EAI custom rest endpoint (ie one that is NOT used from guided setup aka setup.xml).

Failing that, can anyone see what I'm doing wrong, or can you tell me if there are any tricks to get some kind of debugging or troubleshooting going?