flexible method
Make a StatefulWidget Flexible. Example:
Row(
 children: [
  TextField(controller: TextEditingController()).flexible(),
  TextField(controller: TextEditingController()).flexible(),
 ],
 ),
Implementation
Flexible flexible({Key? key, int flex = 1, FlexFit fit = FlexFit.loose}) {
  return Flexible(
    key: key,
    flex: flex,
    fit: fit,
    child: this,
  );
}