call method
Implementation
@override
String? call(TerminalKeyboardEvent event) {
if (event.type == TerminalKeyEventType.release) return null;
if (event.key != TerminalKey.backspace) return null;
if (!event.state.backarrowKeyMode) return null;
final prefix = switch (event.alt) {
true => '\x1b',
false => '',
};
return '$prefix\b';
}