def METHOD_NAME(request: tasks_fn.CallableRequest) -> https_fn.Response:
    """Add an onboarding event to a user's Google Calendar.
    Retrieves and deletes the access token that was saved to Cloud Firestore.
    """
    if "uid" not in request.data:
        return https_fn.Response(
            status=https_fn.FunctionsErrorCode.INVALID_ARGUMENT,
            response="No user specified.",
        )
    uid = request.data["uid"]
    user_record: auth.UserRecord = auth.get_user(uid)
    if user_record.email is None:
        return https_fn.Response(
            status=https_fn.FunctionsErrorCode.INVALID_ARGUMENT,
            response="No email address on record.",
        )
    firestore_client: google.cloud.firestore.Client = firestore.client()
    user_info = (
        firestore_client.collection("user_info").document(uid).get().to_dict()
    )
    if (
        not isinstance(user_info, dict)
        or "calendar_access_token" not in user_info
    ):
        return https_fn.Response(
            status=https_fn.FunctionsErrorCode.PERMISSION_DENIED,
            response="No Google OAuth token found.",
        )
    calendar_access_token = user_info["calendar_access_token"]
    firestore_client.collection("user_info").document(uid).update(
        {"calendar_access_token": google.cloud.firestore.DELETE_FIELD}
    )
    google_credentials = google.oauth2.credentials.Credentials(
        token=calendar_access_token
    )
    calendar_client = googleapiclient.discovery.build(
        "calendar", "v3", credentials=google_credentials
    )
    calendar_event = {
        "summary": "Onboarding with ExampleCo",
        "location": "Video call",
        "description": "Walk through onboarding tasks with an ExampleCo engineer.",
        "start": {
            "dateTime": (datetime.now() + timedelta(days=3)).isoformat(),
            "timeZone": "America/Los_Angeles",
        },
        "end": {
            "dateTime": (
                datetime.now() + timedelta(days=3, hours=1)
            ).isoformat(),
            "timeZone": "America/Los_Angeles",
        },
        "attendees": [
            {"email": user_record.email},
            {"email": "onboarding@example.com"},
        ],
    }
    calendar_client.events().insert(
        calendarId="primary", body=calendar_event
    ).execute()
    return https_fn.Response("Success")