V3 cli play equivalent for v2.2 play --stream=i option

In the blog post What's new in asciinema - part II: the recorder · asciinema blog there was a new feature for v2.2

asciinema rec --stdin demo.cast
asciinema play --stream=i demo.cast | asciinema rec new.cast

With the v3 release, I can see rec -I but I am failing to see how to reproduce this nifty trick. Is it possible?

thanks in advance

regards

Pam