{{- $symbol := "" -}}
{{- $text := "" -}}
{{- if .IsNamedParams -}}
  {{ $symbol = .Get "symbol" }}
  {{ $text = .Params.text | default (printf "$%s" $symbol) }}
{{- else -}}
  {{ $symbol = .Get 0 }}
  {{ $text = printf "$%s" $symbol }}
{{- end -}}
<a href="https://finance.yahoo.com/quote/{{ $symbol }}">{{ $text }}</a>