func (s status) String() string {
	switch s {
	case UNKNOWN:
		return "UNKNOWN"
	case TODO:
		return "TODO"
	case DONE:
		return "DONE"
	default:
		return ""
	}
}
String returns the string representation of s. This can be generated
by stringer tool, though this function is hand-written.
package task
import (
	"errors"
	"fmt"
	"strconv"
	"time"
)
type status int
const (
	UNKNOWN status = iota
	TODO
	DONE
)