wtf! is this

But it's still a double, isn't it? double + single.

Agreed

Same for python

The ternary operator is redundant here.

Interesting

Wow! Nice!

Nice.

@aerotune @travelerspb I see what you mean. I appreciate that not mutating the original string is better, I added a new solution here: http://www.codewars.com/kata/reviews/55f20b5169b42aa91b0000dc/groups/5b1ccdb7777ab7180e000130
What I strive for is to go the 'confident ruby' way of narrative code, where managing the input is clearly distinguished from the work performed on that input.
Thanks for your comments!

definetely a bad practice

Very interesting method,

send() takes an operator string, as if this challenge was perfectly set up for your solution.

Nice! I always forget about Set...

Like!