glg.go
func (g *Glg) PrintFunc(f func() string) error {
	if g.isModeEnable(PRINT) {
		return g.out(PRINT, "%s", f())
	}
	return nil
}
func (g *Glg) PrintFunc(f func() string) error {
	if g.isModeEnable(PRINT) {
		return g.out(PRINT, "%s", f())
	}
	return nil
}
// PrintFunc outputs Print log returned from the function