def process(row)
      @inst.tweakers.each do |tweaker|
        row = tweaker.tweak row
        return nil unless row
      end
      @inst.consumers.each do |consumer|
        consumer << row
      end
    end
def process(row)
      @inst.tweakers.each do |tweaker|
        row = tweaker.tweak row
        return nil unless row
      end
      @inst.consumers.each do |consumer|
        consumer << row
      end
    end
tweak & consume one row