How to convert ebooks in bulk with Python and Calibre

[janoroot]

I wrote a Python script that uses Calibre to do ebook conversion in bulk. Multiple child processes are opened in parallel with the help of the module subprocess. The script has a command-line interface from which the user can specify the input directory of ebooks, the format for conversion, and also an output directory.

https://orthodoxpirate.blogspot.com/2022...-with.html

I want to improve the code. I am looking for harsh criticism.