Often I encounter similar instances where something fundamental is missing from golang's standard packages and no third-party library exists.

Authors cite superior support for tty on variant archs. But by using golang as the central pipeline manager, calls to jsdom or PIL or ffmpeg simply become another stage in the pipeline. Any number of Python microservices can be composed, while retaining golang as the glue providing timeouts, sync, etc.

Still, whatever works for the Asciinema is OK in my book. Great service and will be recommending to all!