Consul-template how to query value from specific key of service meta

Consul
6

Hey @blake,
I have one additional question regarding template you have provided. How it would be possible to additional add an if statement according which if meta key path is not defined for service then location directive should stay unchanged like

 location / {
    proxy_pass http://{{ $service }};
    health_check;
  }
{{ end }}

Thank you.