logger

type Logger interface {
	Println(format string, a ...interface{})
	Printf(format string, a ...interface{})
	Infow(msg string, kv ...interface{})
	Actionf(format string, a ...interface{})
	Generatef(format string, a ...interface{})
	Waitingf(format string, a ...interface{})
	Successf(format string, a ...interface{})
	Warningf(format string, a ...interface{})
	Failuref(format string, a ...interface{})
	Write(p []byte) (n int, err error) // added to satisfy io.Writer interface
}