func (fms *FailureMatches) UnmarshalJSON(b []byte) error {
	var s string
	if err := json.Unmarshal(b, &s); err == nil {
		*fms = []string{s}
		return nil
	}
	var ss []string
	if err := json.Unmarshal(b, &ss); err != nil {
		return err
	}
	*fms = FailureMatches(ss)
	return nil
}
UnmarshalJSON unmarshals FailureMatches.
package daisy
import (
	"context"
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
	"sync"
	"time"
	"google.golang.org/api/googleapi"
)
const (
	defaultInterval = "10s"
)
var (
	serialOutputValueRegex = regexp.MustCompile(".*<serial-output key:'(.*)' value:'(.*)'>")
)
type WaitForInstancesSignal []*InstanceSignal
type WaitForAnyInstancesSignal []*InstanceSignal
type FailureMatches []string