def get_catalog_value catalog, id, key
      catalog_exists? catalog
      if @report.at_css("#{catalog}").at("[@id='#{id}']")
        @report.at_css("#{catalog}").at("[@id='#{id}']")["#{key}"]
      else
        return false
      end
    end
def get_catalog_value catalog, id, key
      catalog_exists? catalog
      if @report.at_css("#{catalog}").at("[@id='#{id}']")
        @report.at_css("#{catalog}").at("[@id='#{id}']")["#{key}"]
      else
        return false
      end
    end
get an attribute from a catalog entry
 @param [String] catalog Name of the catalog. One of {OpenTox::QMRFReport::CATALOGS CATALOGS}.
 @param [String] id entry id in the catalog
 @param [String] key returns value of a key in a catalog node
 @return [String, false] returns value of a key in a catalog node or false if catalog entry do not exists.