func split2(s, sep string) (string, string, bool) {
	spl := strings.SplitN(s, sep, 2)
	if len(spl) < 2 {
		return "", "", false
	}
	return spl[0], spl[1], true
}
split2 returns the values from strings.SplitN(s, sep, 2).
If sep is not found, it returns ("", "", false) instead.
package grpcutil
import (
	"strings"
	"google.golang.org/grpc/resolver"
)