code: def follow(*models)
        models.each do |model|
          unless model == self or self.follower_of?(model) or model.followee_of?(self) or self.cannot_follow.include?(model.class.name) or model.cannot_followed.include?(self.class.name)
            model.followers.create!(:f_type => self.class.name, :f_id => self.id.to_s)
            model.followed_history << self.class.name + '_' + self.id.to_s
            model.save
            self.followees.create!(:f_type => model.class.name, :f_id => model.id.to_s)
            self.follow_history << model.class.name + '_' + model.id.to_s
            self.save
          end
        end
      end
docs: follow some model