How did I install Varnish 6.1 to Debian 10?

The varnishcache/varnish60lts repository (long-term support packages for Varnish 6.x) on does not provide a package for Debian 10:

The official Debian repository provides only an outdated 6.1.1 version of Varnish:

This version of Varnish was released at 2018-10-26: .

It can be installed via the standard Debian way:

aptitude install varnish

See also: How did I install Varnish 6.4 to Debian 10?