def negative_keyword(text = nil, match = CriterionKeyword::BROAD, &block)
      negative_criterion = NegativeAdGroupCriterion.new(self)
      criterion = CriterionKeyword.new(self, text, match, &block)
      negative_criterion.criterion = criterion
      @criterions ||= []
      @criterions.push( negative_criterion )
      negative_criterion
    end
def negative_keyword(text = nil, match = CriterionKeyword::BROAD, &block)
      negative_criterion = NegativeAdGroupCriterion.new(self)
      criterion = CriterionKeyword.new(self, text, match, &block)
      negative_criterion.criterion = criterion
      @criterions ||= []
      @criterions.push( negative_criterion )
      negative_criterion
    end
criterion management