call method
Implementation
@override
String? call(TerminalKeyboardEvent event) {
if (event.type == TerminalKeyEventType.release) return null;
if (event.state.modifyOtherKeysMode != 2) return null;
// A character Option composed is text, not Alt plus a key: send it as
// typed.
if (isMacOptionComposedText(event)) return event.text;
final codepoint = _codepoint(event);
if (codepoint == null) return null;
if (!_shouldModify(event, codepoint)) return null;
return '\x1b[27;${_encodedModifiers(event)};$codepoint~';
}