gstring.go
func Fprintm(w io.Writer, format string, args map[string]interface{}) (n int, err error) {
	f, a := gformat(format, args)
	return fmt.Fprintf(w, f, a...)
}
func Fprintm(w io.Writer, format string, args map[string]interface{}) (n int, err error) {
	f, a := gformat(format, args)
	return fmt.Fprintf(w, f, a...)
}
// Fprintm writes formatted string to provided writer.
// This is same as fmt.Fprintf, but uses gstring formatting.