"""Great Expectations suite definitions for the pipeline.

Lesson 03 fills this module with a suite that validates the L02 Parquet
output: required columns, null checks, type checks, and a value-set
expectation on ``type`` to surface drift.

This Plan-A skeleton just refuses to run.
"""

from __future__ import annotations


def build_suite() -> object:
    """Return the Great Expectations suite for the gharchive events table.

    Returns:
        A ``great_expectations.core.expectation_suite.ExpectationSuite``.

    Raises:
        NotImplementedError: until Lesson 03 fills this in.
    """
    raise NotImplementedError(
        "build_suite is a Plan-A stub; Lesson 03 fills this in."
    )


def main() -> None:
    raise SystemExit(
        "quality.expectations has no implementation yet - start at lesson "
        "03 of the Data Engineering course."
    )


if __name__ == "__main__":
    main()