web3 connection in flutter

ishwar.dart

import 'package:flutter/material.dart';
import 'package:http/http.dart';
import 'package:web3dart/web3dart.dart';

void main() {
  runApp(MaterialApp(
    home: EthApp(),
    title: 'web3 flutter app',
  ));
}

class EthApp extends StatefulWidget {
  @override
  _EthAppState createState() => _EthAppState();
}

class _EthAppState extends State<EthApp> {
  @override
  void initState() {
    _loadBalance();
    super.initState();
  }

  void _loadBalance() async {
  var _client = Web3Client(
        'https://mainnet.infura.io/v3/ie8b3da9156fd4b4f8f8cdac7e085e1e0',
        Client());
        final int BlockNumber = await _client.getBlockNumber();
        print(BlockNumber);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('web3 flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Align(
          alignment: Alignment.center,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: 'this is just a demo',
          ),
        ),
      ),
    );
  }
}