Occasionally it is very useful to refer to a host in a group by an index.  For example, if you are setting up Apache or HAProxy, you may need to push a configuration file out to each host that can redirect to all other hosts.

It is actually quite easy to refer to the hosts in a group by index, but its not necessarily easy to google it unfortunately.  Here is the syntax for the first 3 hosts in a group:

{{groups['coordinators'][0]}}
{{groups['coordinators'][1]}}
{{groups['coordinators'][2]}}