filesystem abstraction offering one API to many filesystems

 Flysystem is a filesystem abstraction which allows you to easily swap out a
 local filesystem for a remote one.
 .
 Goals:
  * Have a generic API for handling common tasks across multiple file
    storage engines.
  * Have consistent output which you can rely on.
  * Integrate well with other packages and frameworks.
  * Be cacheable.
  * Emulate directories in systems that support none, like AwsS3.
  * Support third party plugins.
  * Make it easy to test your filesystem interactions.
  * Support streams for big file handling.