func (mt MatchType) String() string {
	switch mt {
	case None:
		return "None"
	case Subset:
		return "Subset"
	case Exact:
		return "Exact"
	case Superset:
		return "Superset"
	default:
		return fmt.Sprintf("invalid MatchType %d", mt)
	}
}
String() implements Stringer interface for MatchType
package cpedict
import (
	"fmt"
	"github.com/facebookincubator/nvdtools/wfn"
)
type MatchType int
const (
	None MatchType = iota
	Subset
	Exact
	Superset
)