{{ $ref := "" }}
{{ $target := "" }}
{{ with .Get "href" }}
  {{ $ref = . }}
  {{ $target = "_blank" }}
{{ end }}
{{ with .Get "relref" }}
  {{ $ref = relref $ . }}
{{ end }}
<a {{ with $ref }} href="{{.}}" {{ end }} {{ with $target }} target="{{.}}" {{ end }} class="book-btn{{ with .Get "class" }} {{ . }}{{ end }}">
  {{ $.Inner }}
</a>
