slog::slog_log

macro_rules! slog_log {
    ($l:expr, $lvl:expr, $msg:expr) => { ... };
    ($l:expr, $lvl:expr, $msg:expr, $($k:expr => $v:expr),*) => { ... };
}

Log message of a given level (alias)

Prefer shorter version, unless it clashes with existing log crate macro.