hero.ts

export class Hero {
  private _id: number;
  private _name: string;
  private _power: string
  private _alterEgo: string
  
  constructor(
    public id: number,
    public name: string,
    public power: string,
    public alterEgo?: string
  ) {
      this._id = id;
      this._name = name;
      this._power = power;
      this._alterEgo = alterEgo;
  }
}