[lucasoshiro]

Kotlin also has it, I can tell you that it's really useful

[cempaka]

Ruby has had this in the same form as "_1" for a while (and the obvious other indexes in the case of multiple params), but I agree Kotlin's "it" reads much better.

[onedognight]

Groovy has had “it” for a while. I suspect it predates Kotlin’s usage.

[pledg]

Also matches Groovy