Current status of beginless range (experimental or not)
A beginless range was experimentally introduced in Ruby 2.7.0:
Is it still experimental feature or not?
Updated by xtkoba (Tee KOBAYASHI) about 2 months ago
AFAIK, there was no such message as "Beginless range is experimental, and the behavior may change in future versions of Ruby!" in the first place. I am not responsible for this, but my feeling is that this feature is not quite unstable now.