def save_as(pathname, prefix = nil)
      if File.exist?(pathname)
        return if Config.new(pathname) == self
      end

      pathname.open('w') { |file| file << to_s(prefix) }
    end
def save_as(pathname, prefix = nil)
      if File.exist?(pathname)
        return if Config.new(pathname) == self
      end

      pathname.open('w') { |file| file << to_s(prefix) }
    end
Writes the serialized representation of the internal data to the given
 path.

 @param  [Pathname] pathname
         The file where the data should be written to.

 @return [void]