Within the discogs account under Settings > Developers create a personal access token (API) and copy it

Open the config.yml and paste the token and your mail address:

credentials:

  token: 'ROUItMiVIbofqWZOqmgAZkCvLpcVRBYhYjsLMYNc'
  mailReceiver: # ADD YOUR MAIL ADDRESS WHERE TO RECEIVE!
  mailSender: # ADD YOUR MAIL ADDRESS WHERE TO SEND FROM!
  senderPassword: # SENDER PASSWORD
...

and save it.

$ python discogsScreener.py

The bot in the above screenshot has found 14 changes for the first cat and 300 for the second cat number. Each change (containing cat number, discogs-release-number) are sent to the user via mail and will be dropped persistently in a local json-database.