"--right2left" exist?

Hello.
My name is Akihiro, aged 37, japanese.
This is my first post on this forum.
If there's something wrong with my post, please let me know.

I'm just testing ebook-convert command for my manga like following.
$ ebook-convert sample.azw3 test.epub --right2left
:
ebook-convert: error: no such option: --right2left

And I got error above.
right2left option exists on the manual(http://manual.calibre-ebook.com/cli/ebook-convert.html.)

If right2left option is abandoned, is there any alternative to implement the feature?

Thanks in advance.
Akihiro

$ ebook-convert --version
ebook-convert (calibre 2.20.0)