_dasherize

# File activesupport/lib/active_support/xml_mini.rb, line 142
    def _dasherize(key)
      # $2 must be a non-greedy regex for this to work
      left, middle, right = /\A(_*)(.*?)(_*)\Z/.match(key.strip)[1,3]
      "#{left}#{middle.tr('_ ', '--')}#{right}"
    end