Dart/Flutter dialog imitation with streams

Bubble.dart

import 'package:flutter/material.dart';
import 'func.dart';

class Message {
  Message(this.text, this.isMe);

  String text;
  bool isMe;
}

class Bubble extends StatelessWidget {
  Bubble({this.message, this.isMe});

  final String message;
  final bool isMe;

  @override
  Widget build(BuildContext context) {
    final bg = isMe ? Colors.lightBlue : Colors.greenAccent.shade200;
    final align = isMe ? CrossAxisAlignment.start : CrossAxisAlignment.end;
    final radius = BorderRadius.only(
      topRight: Radius.circular(isMe ? 5.0 : 0),
      topLeft: Radius.circular(isMe ? 0 : 5.0),
      bottomLeft: Radius.circular(isMe ? 10.0 : 5.0),
      bottomRight: Radius.circular(5.0),
    );

    return Column(
      crossAxisAlignment: align,
      children: <Widget>[
        Container(
            margin: const EdgeInsets.all(3.0),
            padding: const EdgeInsets.all(8.0),
            decoration: BoxDecoration(
              color: bg,
              borderRadius: radius,
            ),
            child: Stack(
              children: <Widget>[
                Padding(
                    padding: EdgeInsets.only(right: 48.0),
                    child: Text(
                      message,
                      style: TextStyle(
                        fontSize: 20.0,
                      ),
                    )),
              ],
            ))
      ],
    );
  }
}

class Dialogue extends StatelessWidget {
  Dialogue({this.messages});

  final Stream<Message> messages;

  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
      stream: aggregate(messages),
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        if (snapshot.hasError) {
          return Text("Dialogue stream failure :(");
        } else {
          final msgs = snapshot.data as List<Message>;
          return Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: msgs
                  .map((msg) => Bubble(
                        message: msg.text,
                        isMe: msg.isMe,
                      ))
                  .toList());
        }
      },
    );
  }
}

func.dart

// Miscellanious utilities
import 'dart:async';

Stream<List<T>> aggregate<T>(Stream<T> s) async* {
  List<T> res = [];
  await for (T item in s) {
    res.add(item);
    yield res;
  }
}

Stream<T> fromIterableDelayed<T>(Iterable<T> i, Duration delay) async* {
  for (T item in i) {
    await Future.delayed(delay);
    yield item;
  }
}

main.dart

import 'package:flutter/material.dart';
import 'bubble.dart';
import 'func.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Welcome to Flutter (title)',
        home: Scaffold(
            appBar: AppBar(
              title: Text('Welcome to Flutter'),
            ),
            backgroundColor: Colors.blueGrey.shade50,
            body: Padding(
                padding: EdgeInsets.only(
                  top: 10.0,
                ),
                child: Dialogue(
                    messages: fromIterableDelayed([
                  Message("Hi!", true),
                  Message("My name is", true),
                  Message("What?", false),
                  Message("My name is", true),
                  Message("Who?", false),
                  Message("My name is", true),
                  Message("chka-chka Stream Shady!", true),
                ], Duration(milliseconds: 1500))))));
  }
}