commonmarker --version (return code: 0)
commonmarker 0.17.13
commonmarker --help (return code: 0)
Usage: commonmarker [--html-renderer] [--list-extensions] [--extension=EXTENSION] [FILE..]
Convert one or more CommonMark files to HTML and write to standard output.
If no FILE argument is provided, text will be read from STDIN.
With --html-renderer, use the HtmlRenderer renderer rather than the native C
renderer.
With --extension=EXTENSION, EXTENSION will be used for parsing, and HTML
output unless --html-renderer is specified.