code: function validate(key) {
          var type = getType(key);
          if (type === "array") {
              for (var i = 0; i < key.length; i++) {
                  validate(key[i]);
              }
          }
          else if (!types[type] || (type !== "string" && isNaN(key))) {
              throw idbModules.util.createDOMException("DataError", "Not a valid key");
          }
      }
docs: Keys must be strings, numbers, Dates, or Arrays