kvlog/writer.go
func NewWriter(out io.Writer) *Writer {
	w := &Writer{
		printer: newPrinter(out),
	}
	return w
}
func NewWriter(out io.Writer) *Writer {
	w := &Writer{
		printer: newPrinter(out),
	}
	return w
}
// NewWriter creates writer that logs messages to out. If the output writer is a terminal
// device, the output will be formatted for improved readability.