https://nodejs.org/api/process.html#process_process

Copies from src to dst until either EOF (null) is read from src or an error occurs. It resolves to the number of bytes copied or rejects with the first error encountered while copying.

TODO: Also accept 'path' parameter as a Node polyfill Buffer or URL type once these are implemented. See https://github.com/denoland/deno/issues/3403

Create a Reader from a ReadableStreamDefaultReader.