Macro println_warning 

macro_rules! println_warning {
    ($($arg:tt)*) => { ... };
}

Prints a warning message with yellow background and white text.

Supports format string syntax like the format! macro:

• println_warning!(body) - Simple string with no arguments
• println_warning!(body, error) - Positional arguments replaced by {}
• println_warning!(body, error = value) - Named arguments replaced by {error} (Rust 1.58+)