apply method
Implementation
@override
String apply(String value) => values.entries.fold(value, (acc, element) {
final finalValue = switch (element.value) {
String() => element.value,
int() => element.value.toString(),
_ => throw Exception('Invalid type')
};
return acc
.replaceAll('{${element.key}}', finalValue)
.replaceAll('{{ ${element.key} }}', finalValue);
});