code: def add_attribute(node, key, name, value)
        node[:attributes!] ||= {}
        node[:attributes!][key] ||= {}
        if node[:attributes!][key].include?(name)
          node[:attributes!][key][name] = arrayize(node[:attributes!][key][name])
          node[:attributes!][key][name] << value
        else
          node[:attributes!][key][name] = value
        end
      end
docs: Adds Savon attribute for given node, key, name and value.