void type is used to build the go code < 1.10

utils.go

@@ -7,6 +7,9 @@ import (
 	"github.com/DATA-DOG/godog/colors"
 )
 
+// build < go.10
+type void struct{}
+
 var (
 	red    = colors.Red
 	redb   = colors.Bold(colors.Red)