Feature #17133
Updated by S_H_ (Shun Hiraoka) about 4 years ago
`Kernel#iterator?` was mildly deprecate sicne`1.8.6`, as far as I checked [ruby-doc](https://ruby-doc.org/core-1.8.6/Kernel.html#method-i-iterator-3F).
I think it better, to deprecated warn added(or delete `Kernel#iterator?`).
pull request:
https://github.com/ruby/ruby/pull/3467