Macro error_once 

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

Logs a message at the error level exactly once per callsite.

The first invocation logs the message; all subsequent calls are silently dropped.

Example

use log_debounce::error_once;

// Logs only the first time this line is reached
error_once!("Failed to load critical configuration");