def serialize(params)
      params.each do |key, value|
        send("#{key}=", value) if respond_to?(key)
      end    
    end
def serialize(params)
      params.each do |key, value|
        send("#{key}=", value) if respond_to?(key)
      end    
    end
def to_s
 	self.respond_to? :to_nfe ? to_nfe : super
 end