{{ $parts := strings.Split (strings.Substr . 1) "T" }}
{{ $timePart := (index $parts 1 | strings.ToLower) }}
{{ if eq $timePart "" }}{{ $timePart = "0s" }}{{ end }}
{{ $duration := time.ParseDuration $timePart }}
{{ $dayCount := replaceRE `^(\d+)D$` `$1` (index $parts 0) }}
{{ with $dayCount }}
  {{ $asHours := printf "%dh" (mul (int .) 24) }}
  {{ $origin := time "1970-01-01" }}
  {{ $later := $origin.Add (time.ParseDuration $asHours) }}
  {{ $later = $later.Add $duration }}
  {{ $duration = $later.Sub $origin }}
{{ end }}
{{ return $duration }}