func (b *Result) SetUnreachable() {
	b.Status = -1
	b.Trace = nil
}
SetUnreachable makes `b` known to be unreachable.
package reach
import (
	"fmt"
	"time"
	"github.com/go-air/gini/z"
)
type Result struct {
	M         z.Lit          
	Status    int            
	Depth     int            
	Dur       time.Duration  
	Trace     *Trace        `json:"-"`  
	Invariant []z.Lit       `json:"-"`  
}
func (b *Result) String() string {
	return fmt.Sprintf("bad[%s]: status=%s depth=%d dur=%s",
		b.M, b.FormatStatus(), b.Depth, b.Dur)
}
func (b *Result) FormatStatus() string {
	switch b.Status {
	case -1:
		return "unreachable"
	case 1:
		return "reachable"
	case 0:
		return "unknown"
	default:
		panic("unreachable")
	}
}
func (b *Result) IsSolved() bool {
	return b.Status != 0
}
func (b *Result) IsReachable() bool {
	return b.Status == 1
}
func (b *Result) SetReachable(t *Trace) {
	b.Status = 1
	b.Trace = t
}
func (b *Result) IsUnreachable() bool {
	return b.Status == -1
}