How to use strapi upload plugin inside code in version 3.1.6?

Question

In version 3.0.0-beta.18 I used this :

const buffers = await uploadService.bufferize(files.attachment);
  await uploadService.upload(buffers, config);

to download files. And now I have switched to 3.1.6 and this method returns an error:

===Error===
 TypeError: uploadService.bufferize is not a function 

I try to use streamToBuffer but it doesn't work