Ruby #itself

I had an array which looked something like this:

arr = [1, 2, 2, 2, 1, 1, 3]

and what I wanted was to group consecutive repeats of the same value together. I can do this with chunk and map.

arr.chunk { |x| x }.map(&:first)
#=> [1, 2, 1, 3]

I could use Ruby 2.7's number arguments to maybe make it a little less bizarre:

arr.chunk { _1 }.map(&:first)

but that's still really weird looking.

Instead, there is a really nice method Kernel#itself which does nothing but return back the object it's called on. This means I can write the much more beautiful:

arr.chunk(&:itself).map(&:first)