app/lib/my_tools/my_tools.dart

import 'package:flutter/material.dart';

class MyTools{
    toPage(context, page, then,{bool noBack = false}){
      if(noBack){
        Navigator.pushAndRemoveUntil(
            context,
            MaterialPageRoute(builder: (context) => page),
                (route) => route == null);
      }else{
        Navigator.push(context, MaterialPageRoute(builder: (context) => page))
            .then(then);
      }
    }
}