code: function(instance) {
        let type = typeof instance;
        if (!instance) {
          return "falsey";
        } else if (Array.isArray(instance)) {
          if (
            instance.length === 2 &&
            typeof instance[0] === "number" &&
            typeof instance[1] === "number"
          ) {
            return "range";
          } else {
            return "array";
          }
        } else if (type === "object") {
          if (instance instanceof RegExp) {
            return "regexp";
          } else if (instance.hasOwnProperty("highlight")) {
            return "custom";
          }
        } else if (type === "function" || type === "string") {
          return type;
        }
  
        return "other";
      }
docs: returns identifier strings that aren't necessarily "real" JavaScript types