class Thin::Response                        # This class specifies it's own each method which yields multiple times.
    def each
      yield head                              # Once for the status/headers
      if @body.is_a?(String)
        yield @body                           # Again if the response body is a String
      else
        @body.each { |chunk| yield chunk }    # And it enumerates over anything else.
      end                                     # This is the place to hook into.
    end
  end

# This is the block getting yielded to!
    @response.each do |chunk|
      trace { chunk }
      send_data chunk
    end