code: function toJSON(key) {
      var O = toObject(this);
      var pv = toPrimitive(O);
      return typeof pv == 'number' && !isFinite(pv) ? null :
        (!('toISOString' in O) && classof(O) == 'Date') ? toISOString.call(O) : O.toISOString();
    }
docs: eslint-disable-next-line no-unused-vars