logger.go
func (dl *DefaultLogger) Trace(message string, params ...interface{}) {
	dl.logger.Tracef(fmt.Sprintf("%s %s", caller(), message), params...)
}
func (dl *DefaultLogger) Trace(message string, params ...interface{}) {
	dl.logger.Tracef(fmt.Sprintf("%s %s", caller(), message), params...)
}
// Trace formats a given message according to given params to log with level Trace.