It's a magic comment, a feature from Ruby 2.3+ [0]. Not sure what set dhh (David Heinemeier Hansson, creator of the Ruby on Rails web framework) off about this,

It's a magic comment, a feature from Ruby 2.3+ [0]. Not sure what set dhh (David Heinemeier Hansson, creator of the Ruby on Rails web framework) off about this, but I'm guessing it improves performance and was a concession after alternatives were exhausted. 0. https://stackoverflow.com/questions/37799296/ruby-what-does-the-comment-frozen-string-literal-true-do#37799399 https://stackoverflow.com/questions/37799296/ruby-what-does-...