How to use the firebase-functions.Change.fromObjects function in firebase-functions

const { Change } = require("firebase-functions");

  const newSnap =
    proto.data.value &&
    (app.firestore() as any).snapshot_(proto.data.value, new Date().toISOString(), "json");
  const oldSnap =
    proto.data.oldValue &&
    (app.firestore() as any).snapshot_(proto.data.oldValue, new Date().toISOString(), "json");

  let data;
  switch (proto.context.eventType) {
    case "providers/cloud.firestore/eventTypes/document.write":
      data = Change.fromObjects(oldSnap, newSnap);
      break;
    case "providers/cloud.firestore/eventTypes/document.delete":
      data = Change.fromObjects(oldSnap, newSnap);
      break;
    default:
      data = newSnap && oldSnap ? Change.fromObjects(oldSnap, newSnap) : newSnap;
  }

  const resourcePath = proto.context.resource.name;
  const params = _extractParamsFromPath(trigger.definition.eventTrigger.resource, resourcePath);

  const ctx = {
    eventId: proto.context.eventId,
    timestamp: proto.context.timestamp,
    params,
    auth: {},
    authType: "UNAUTHENTICATED",
  };

const proto = JSON.parse(body);

        const newSnap =
          proto.data.value &&
          (app.firestore() as any).snapshot_(proto.data.value, new Date().toISOString(), "json");
        const oldSnap =
          proto.data.oldValue &&
          (app.firestore() as any).snapshot_(proto.data.oldValue, new Date().toISOString(), "json");

        let data;
        switch (proto.context.eventType) {
          case "providers/cloud.firestore/eventTypes/document.write":
            data = Change.fromObjects(oldSnap, newSnap);
            break;
          case "providers/cloud.firestore/eventTypes/document.delete":
            data = Change.fromObjects(oldSnap, newSnap);
            break;
          default:
            data = newSnap && oldSnap ? Change.fromObjects(oldSnap, newSnap) : newSnap;
        }

        const path = proto.context.resource.name;
        const params = _extractParamsFromPath(trigger.eventTrigger.resource, path);

        const ctx = {
          eventId: proto.context.eventId,
          timestamp: proto.context.timestamp,
          params,
          auth: {},
          authType: "UNAUTHENTICATED",
        };

proto.data.value &&
    (app.firestore() as any).snapshot_(proto.data.value, new Date().toISOString(), "json");
  const oldSnap =
    proto.data.oldValue &&
    (app.firestore() as any).snapshot_(proto.data.oldValue, new Date().toISOString(), "json");

  let data;
  switch (proto.context.eventType) {
    case "providers/cloud.firestore/eventTypes/document.write":
      data = Change.fromObjects(oldSnap, newSnap);
      break;
    case "providers/cloud.firestore/eventTypes/document.delete":
      data = Change.fromObjects(oldSnap, newSnap);
      break;
    default:
      data = newSnap && oldSnap ? Change.fromObjects(oldSnap, newSnap) : newSnap;
  }

  const resourcePath = proto.context.resource.name;
  const params = _extractParamsFromPath(trigger.definition.eventTrigger.resource, resourcePath);

  const ctx = {
    eventId: proto.context.eventId,
    timestamp: proto.context.timestamp,
    params,
    auth: {},
    authType: "UNAUTHENTICATED",
  };

  new EmulatorLog("DEBUG", "runtime-status", `Requesting a wrapped function.`).log();
  const func = trigger.getWrappedFunction();