formatter.rb in rouge-3.3.0

- old
+ new

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*- #
+# frozen_string_literal: true
 
 module Rouge
   # A Formatter takes a token stream and formats it for human viewing.
   class Formatter
     # @private
@@ -31,10 +32,10 @@
 
     # Format a token stream.
     def format(tokens, &b)
       return stream(tokens, &b) if block_given?
 
-      out = ''
+      out = String.new('')
       stream(tokens) { |piece| out << piece }
 
       out
     end
 