func NewSimpleManifestReference(ref swarm.Address, l file.LoadSaver) (Interface, error) {
	m := &simpleManifest{
		manifest:  simple.NewManifest(),
		reference: ref,
		ls:        l,
	}
	err := m.load(context.Background(), ref)
	return m, err
}
NewSimpleManifestReference loads existing simple manifest.
package manifest
import (
	"context"
	"errors"
	"fmt"
	"github.com/ethsana/sana/pkg/file"
	"github.com/ethsana/sana/pkg/manifest/simple"
	"github.com/ethsana/sana/pkg/swarm"
)
const (
	ManifestSimpleContentType = "application/bzz-manifest-simple+json"
)
type simpleManifest struct {
	manifest simple.Manifest
	reference swarm.Address
	ls        file.LoadSaver
}
func NewSimpleManifest(ls file.LoadSaver) (Interface, error) {
	return &simpleManifest{
		manifest: simple.NewManifest(),
		ls:       ls,
	}, nil
}