def find_items_advanced(params)
      raise ArgumentError unless params[:keywords] or params[:categoryId]
      response = get_json_response(build_request_url('findItemsAdvanced', params))
      response.trim(:findItemsAdvancedResponse)
      
      if response.response.has_key?('searchResult') && response.response['searchResult'].has_key?('item')
        response.results = response.response['searchResult']['item']
      end
      return response
    end
def find_items_advanced(params)
      raise ArgumentError unless params[:keywords] or params[:categoryId]
      response = get_json_response(build_request_url('findItemsAdvanced', params))
      response.trim(:findItemsAdvancedResponse)
      
      if response.response.has_key?('searchResult') && response.response['searchResult'].has_key?('item')
        response.results = response.response['searchResult']['item']
      end
      return response
    end
http://developer.ebay.com/DevZone/finding/CallRef/findItemsAdvanced.html