Writing custom importer

Hi guys ! I am a beginner started to play with rasa. i have made a few small bots. i have Questions and intents in a database and i can convert it into a yml format the only question is i want an example of how to write a custom importer.

You can find examples here.

i have written a function in colab that connects to the data base gets the intents and can create an nlu.yml file as required but the question is that i want to know how to integrate this function in custom importer so that when i run rasa train my intents from the database should also be trained

You can find docs here.