func (fs *fileSystem) Open(ctx context.Context, path string) (http.File, error) {
	return fs.FileSystem.Open(path)
}
Open implements FileSystem.
package store
import (
	"bytes"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"time"
	"golang.org/x/net/context"
	"golang.org/x/net/trace"
)
type FileSystem interface {
	Open(ctx context.Context, path string) (http.File, error)
}
func NewFileSystem(fs http.FileSystem, name string) FileSystem {
	return Trace(&fileSystem{fs}, name)
}
type fileSystem struct {
	http.FileSystem
}