Document template clone

interface Prototype<T> {
  clone(): T;
}

class DeploymentTemplate implements Prototype<DeploymentTemplate> {
  constructor(
    readonly serviceName: string,
    readonly replicas: number,
    readonly labels: Record<string, string>,
  ) {}

  clone(): DeploymentTemplate {
    return new DeploymentTemplate(
      this.serviceName,
      this.replicas,
      { ...this.labels },
    );
  }

  withEnvironment(environment: string): DeploymentTemplate {
    const copy = this.clone();

    return new DeploymentTemplate(
      copy.serviceName,
      copy.replicas,
      {
        ...copy.labels,
        environment,
      },
    );
  }
}

const baseTemplate = new DeploymentTemplate(
  "billing-api",
  2,
  { owner: "payments" },
);

const productionTemplate = baseTemplate.withEnvironment("production");