how to install varnish6 on ubuntu 16.04

[neo]

I used this instruction 
https://packagecloud.io/varnishcache/varnish60/install#manual-deb

put to /etc/apt/sources.list.d/varnishcache_varnish60.list

deb https://packagecloud.io/varnishcache/varnish60/ubuntu/xenial 16.04 
LTS Xenial Xerus main
deb-src https://packagecloud.io/varnishcache/varnish60/ubuntu/xenial 
16.04 LTS Xenial Xerus main

and when do sudo apt-get update got an error:

...

W: The repository 
'https://packagecloud.io/varnishcache/varnish60/ubuntu/xenial 16.04 
Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore 
potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user 
configuration details.
E: Failed to fetch 
https://packagecloud.io/varnishcache/varnish60/ubuntu/xenial/dists/16.04/LTS/source/Sources 
404  Not Found
E: Some index files failed to download. They have been ignored, or old 
ones used instead.
neo at neo:/tmp/varnish-cache$


The whole code: https://paste.ubuntu.com/p/6FkQZbCPf6/

How to install varnish6 ?



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