Function clickhouse_postgres_client::fetch_optional

pub async fn fetch_optional<'c, 'q, 'async_trait, E>(
    sql: &'q str, 
    executor: E
) -> Result<Option<ClickhousePgRow>, SqlxError> where
    E: ClickhouseExecutor<'c, 'q, 'async_trait, ClickhousePgRow>,
    'c: 'async_trait,
    'q: 'async_trait,
    ClickhousePgRow: From<<E::Database as SqlxDatabase>::Row>,