#[macro_export]
macro_rules! with_conn {
    // Usage: with_conn!(&connection, tx_option, ident, |conn|-> { ... })
    ($conn:expr, $tx:expr, $ident:ident, $body:block) => {{
        if let Some(t) = &$tx {
            let $ident = t;
            $body
        } else {
            let $ident = &$conn;
            $body
        }
    }};
}