Ruby - how to redirect to standard input / output streams?

Question

ruby

Hello! There are STDIN, STDOUT, STDERR streams received from an external application.

stdin, stdout, stderr, wait_thr = Open3.popen3('cmd')

How can I redirect them to the standard $stdin, $stdout and $stderr?
I tried $stderr.reopen stderrbut I get

<STDIN> can't change access mode from "r" to "w" (ArgumentError)

I need to implement something like screen to store streams from different applications and easily switch between them