ERROR: The Compose file './docker-compose.yml' is invalid because: Unsupported config option for services.networks: 'app'

Question

I get This error when I execute I try to execute this command docker-compose up Below is my docker-compose.yml

version: '3.4'
services:
  backend:
    build:
      context: ./backend_app
      dockerfile: Dockerfile
    environment:
      DB_HOST: db
      DB_DATABASE: news_app
      DB_USERNAME: root
      DB_PASSWORD: harr
    ports:
      - 8000:8000
    volumes:
      - ./backend_app:/app/backend_app
    depends_on:
      - db
    networks:
      - app
      - db
  frontend:
    build:
      context: ./frontend_app
      dockerfile: Dockerfile
    tty: true
    ports:
      - 3000:3000
volumes:
  - ./frontend_app:/app/frontend_app

depends_on:
  - backend
networks:
  - app


db:
    image: mysql:latest
    environment:
      MYSQL_ROOT_PASSWORD: harr
      MYSQL_DATABASE: news_db
    ports:
    - 3305:3305
    networks:
      - db
phpmyadmin:
    image: phpmyadmin:latest
    ports:
      - 1009:80
    environment:
      - PMA_ARBITRARY=1
networks:
    app:
      driver: bridge
    db: