{{- $keywords := (slice) -}}

{{- with .Keywords -}}
    {{- $keywords = . -}}
{{- else }}
    {{- with .Params.tags -}}
        {{- $keywords = . -}}
    {{- else -}}
        {{- $keywords = site.Params.keywords | default slice -}}
    {{- end -}}
{{- end -}}

{{- delimit $keywords ", " -}}