Event Emitter

Design and implement an EventEmitter class that mimics Node.js-style event handling.
It should support the following methods:

• on(eventName, callback): Register a callback to be called every time the event is triggered.
• once(eventName, callback): Register a one-time callback (removed after first execution).
• off(eventName, callback): Remove a specific callback for an event.
• emit(eventName, ...args): Trigger all callbacks registered for that event with the given arguments.

Input: Method calls to the EventEmitter class.
Output: Appropriate invocations of callbacks.

Example Inputs & Outputs

const emitter = new EventEmitter();

const log = (...args) => console.log(...args);
emitter.on('sayHello', log);
emitter.emit('sayHello', 'Hi!'); // Output: Hi!

emitter.once('sayBye', () => console.log('Bye!'));
emitter.emit('sayBye'); // Output: Bye!
emitter.emit('sayBye'); // No output

emitter.off('sayHello', log);
emitter.emit('sayHello', 'Hi again'); // No output

Constraints & Edge Cases

• off() should not throw errors for unregistered callbacks
• emit() should handle no listeners gracefully
• once() handlers should auto-remove after one call
• Multiple callbacks per event are allowed
• Callbacks should maintain argument order