Macro slog_scope::slog_warn

macro_rules! slog_warn {
    ($ l : expr, # $ tag : expr, $ ($ args : tt) +) => { ... };
    ($ l : expr, $ ($ args : tt) +) => { ... };
}

Log warning level record (alias)

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

See slog_log for documentation.