{{ $current := .RelPermalink }}
{{ $flat := slice }}
{{ range $group := site.Data.sidebar }}
  {{ if $group.items }}
    {{ range $item := $group.items }}
      {{ $flat = $flat | append $item }}
    {{ end }}
  {{ end }}
{{ end }}
{{ $idx := -1 }}
{{ range $i, $item := $flat }}
  {{ if eq ($item.path | relURL) $current }}{{ $idx = $i }}{{ end }}
{{ end }}
{{ if ge $idx 0 }}
<div class="docs-prevnext">
  {{ if gt $idx 0 }}
    {{ $prev := index $flat (sub $idx 1) }}
    <a class="prev" href="{{ $prev.path | relURL }}"><span class="dir">&larr; Previous</span>{{ $prev.label }}</a>
  {{ else }}
    <span></span>
  {{ end }}
  {{ if lt $idx (sub (len $flat) 1) }}
    {{ $next := index $flat (add $idx 1) }}
    <a class="next" href="{{ $next.path | relURL }}"><span class="dir">Next &rarr;</span>{{ $next.label }}</a>
  {{ end }}
</div>
{{ end }}