..this.values_.keys()];
      keys.sort();
      return [
        serializer.getOrAllocateId(this.colorScheme),
        serializer.getOrAllocateId(keys.map(k =>
          serializer.getOrAllocateId(k))),
        ...keys.map(k => this.get(k)),
      ];
    }

    asDictInto_(d) {
      d.values = {};
      for (const [name, value] of this) {
        d.values[name] = tr.b.numberToJson(value);
      }
      if (this.colorScheme) {
        d.colorScheme = this.colorScheme;
      }
    }

    static fromEntries(