def METHOD_NAME(
    self, variable: str, selection: Optional[List[int]] = None
) -> pd.DataFrame:
    """Return truth `variable`, optionally only for `selection` events."""
    if selection is None:
        query = f"select {self._index_column}, {variable} from {self._truth_table}"
    else:
        query = f"select {self._index_column}, {variable} from {self._truth_table} where {self._index_column} in {str(tuple(selection))}"
    with sqlite3.connect(self._database_path) as con:
        data = pd.read_sql(query, con)
    return data