Macro slog::slog_o

macro_rules! slog_o {
    (@ $k:expr => $v:expr, $($args:tt)+) => { ... };
    (@ $k:expr => $v:expr) => { ... };
    (@ $k:expr => $v:expr,) => { ... };
    () => { ... };
    ($($args:tt)+) => { ... };
}

An alternative, longer-name version of o macro

Use in case of macro name collisions