I'm trying to use the `Migrate API` to implement an ETL for some of the content of my `Drupal 8 website`. But the doc doesn't explain how to execute the migration once everything has been set up:

https://www.drupal.org/docs/8/api/migrate-api/executing-migrations

It only explains how to execute the migration using some contributed modules but not how to execute it using the `Drupal APIs`.

Can someone point me to the right documentation or at least give some hints?