HELM template to detect IP address

I was in a need to detect whether the content of a variable is an IP address or not. I guess the function is not perfect, but it fulfills the basic need:

{{/*
Test if the given value is an IP address
*/}}
{{- define "prefix.isIpAddress" -}}
{{- $rc := . -}}
{{- $parts := splitList "." . -}}
{{- if eq (len $parts) 4 -}}
    {{- range $parts -}}
        {{- if and (not (atoi .)) (ne . "0") -}}
            {{- $rc = "" -}}
        {{- end -}}
    {{- end -}}
{{- else -}}
    {{- $rc = "" -}}
{{- end -}}
{{- print $rc }}
{{- end -}}

The function at least detects these values correctly:

{{ include "prefix.isIpAddress" "1.2.3.4" }}
{{ include "prefix.isIpAddress" "1.0.3.4" }}
{{ include "prefix.isIpAddress" "1.2.3.4.5" }}
{{ include "prefix.isIpAddress" "hello" }}
{{ include "prefix.isIpAddress" "hello.svc" }}
{{ include "prefix.isIpAddress" "hello.svc.tld.com" }}