From the author, on reddit:
Made a little mistake in there: you can create FDs with higher numbers using eg.
exec {fd}<>pipe
and they'll generate numbers above 10, plus the variables'll be better for scripting.
The Z shell is a Unix shell that can be used as an interactive login shell and as a command interpreter for shell scripting. Zsh is an extended Bourne shell with many improvements, including some features of Bash, ksh, and tcsh. Zsh was created by Paul Falstad in 1990 while he was a student at Princeton University.
From the author, on reddit:
Made a little mistake in there: you can create FDs with higher numbers using eg.
exec {fd}<>pipe
and they'll generate numbers above 10, plus the variables'll be better for scripting.