iagnostic(otherDiagnostic) {
      return ((otherDiagnostic instanceof Breakdown) &&
              (otherDiagnostic.colorScheme === this.colorScheme));
    }

    addDiagnostic(otherDiagnostic) {
      for (const [name, value] of otherDiagnostic) {
        this.set(name, this.get(name) + value);
      }
      return this;
    }

    /**
     * Add a Value by an explicit name to this map.
     *
     * @param {string} name
     * @param {number} value
     */
    set(name, value) {
      if (typeof name !== 