Folder struct understanding

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Hi,
I am trying to understand the folder struct that's created ros2 pkg create --build-type ament_python robot_pkg. Here is the folder structure

robot_pkg
        ├── package.xml
        ├── resource
        │   └── robot_pkg
        ├── setup.cfg
        ├── setup.py
        ├── test
        │   ├── __pycache__
        │   │   ├── test_copyright.cpython-38-PYTEST.pyc
        │   │   ├── test_flake8.cpython-38-PYTEST.pyc
        │   │   └── test_pep257.cpython-38-PYTEST.pyc
        │   ├── test_copyright.py
        │   ├── test_flake8.py
        │   └── test_pep257.py
        └── robot_pkg
            ├── __init__.py
            ├── mqtt_subscriber.py
            ├── __pycache__
            │   └── __init__.cpython-38.pyc
            └── robot.py

I am more interested in test, resource and __init__.py. Thanks.