Use variadic options to configure Kong.

help.go

@@ -0,0 +1,28 @@
+package kong
+
+import (
+	"io"
+	"text/template"
+)
+
+const defaultHelp = `{{- with .Application -}}
+usage: {{.Name}}
+
+{{- end -}}
+`
+
+var defaultHelpTemplate = template.Must(template.New("help").Parse(defaultHelp))
+
+// WriteHelp to w. If w is nil, the default stdout writer will be used.
+func (k *Kong) WriteHelp(w io.Writer) error {
+	if w == nil {
+		w = k.stdout
+	}
+	ctx := map[string]interface{}{
+		"Application": k.Model,
+	}
+	for k, v := range k.helpContext {
+		ctx[k] = v
+	}
+	return k.help.Execute(w, ctx)
+}