func NewCacheWrapper(src, cache FS, options *CacheOptions) FS {
	if options == nil {
		options = &CacheOptions{}
	}
	return &cacheWrapper{
		src:     src,
		cache:   cache,
		options: options,
	}
}
NewCacheWrapper creates an FS implementation which caches files opened from src into cache.
package storage
import (
	"context"
	"io"
	"time"
)
type CacheOptions struct {
	MaxAge time.Duration
	DefaultExpired bool
	NoData bool
}