def METHOD_NAME(
    source_category: str,
    destination_category: str,
    time: str,
    source_dir: str,
    destination_dir: str,
    dropped_variables: Optional[Set] = None,
):
    """Check that expected variables in the original restart files can be found in
    the coarsened restart files."""
    source = open_category(source_category, time, source_dir)
    result = open_category(destination_category, time, destination_dir)
    if dropped_variables is None:
        dropped_variables = set()
    expected_variables = set(source.data_vars.keys()) - dropped_variables
    result_variables = set(result.data_vars.keys())
    assert expected_variables == result_variables