{{ $title := "Diagram" }}
{{ if .IsNamedParams }}
  {{ with .Get "title" }}
    {{ $title = . }}
  {{ end }}
{{ else }}
  {{ with .Get 0 }}
    {{ $title = . }}
  {{ end }}
{{ end }}

<figure>
  <img
    src='https://g.gravizo.com/svg?{{ .Inner }}'
    alt='{{ $title  }}'
    />
    <figcaption>{{ $title  }}</figcaption>
</figure>