Post age warning for Hugo

PostAgeWarning.html

{{- $PostYear := .Date -}}
{{- $CurrentYear := time.Now -}}
{{- $YearDifU := math.Sub $CurrentYear.Unix $PostYear.Unix -}}
{{- $TPostYear := .Date | time.Format "2006" | int -}}
{{- $YearDif := math.Sub (now.Year | int) $TPostYear -}}
{{- if ge $YearDifU 31536000 -}}
  <p class="notice">
    This post is over {{ if eq $YearDif 1 }} a year{{- else -}}{{- $YearDif }} years{{- end }} old. The information here may be out of date, and may not reflect my current thoughts or opinions.
  </p>
{{- end -}}