About linux : ERROR-In-file-docker-composeyml-service-must-be-a-mapping-not-a-NoneType-how-to-solve-this-problem

I’m trying to install Jenkins in Ubuntu, and I don’t known how to solve this problem. I attach a photo of the error.

Thanks! enter image description here

Line 2 is syntax error. Please check with other example:

version: '3.7'
services:
  jenkins:
    image: jenkins/jenkins:lts
    privileged: true
    user: root
    ports:
      - 8081:8080
      - 50000:50000
    container_name: jenkins
    volumes:
      - ~/jenkins:/var/jenkins_home
      - /var/run/docker.sock:/var/run/docker.sock
      - /usr/local/bin/docker:/usr/local/bin/docker