src/classes/era.ts
export enum Era {
Ancient = <any>'Ancient',
Classical = <any>'Classical',
Medieval = <any>'Medieval',
Renaissance = <any>'Renaissance',
Enlightenment = <any>'Enlightenment',
Industrial = <any>'Industrial',
Modern = <any>'Modern',
Atomic = <any>'Atomic',
Information = <any>'Information',
Future = <any>'Future'
}