## How to add a new node support to TraceCommentor

- Read about the target node information (https://docs.python.org/3/library/ast.html).
- Add a test case.
- Write the implementation and pass all tests.
    - echo the original code. (automatically handled by the parent scope node if not in `flags.APPEND_SOURCE_BY_THEMSELVES`)
    - expression should be evaluated and add comment to each recursively by correct order. (use `cmtor.eval(...)`)
    - statements should be executed. (use `cmtor.exec(...)`)
    - use `pytest -s -q -k` to test new test case first, use `DEBUG` and `PRINT` environment variable to help debugging.