ubuntu@ip-172-31-16-20:~$ sudo apt policy python3
python3:
  Installed: 3.5.1-3
  Candidate: 3.5.1-3
  Version table:
 *** 3.5.1-3 500
        500 http://ap-southeast-2.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status
ubuntu@ip-172-31-16-20:~$