hello i am buliding a simple chatting app. in my apis.dart folder i have created sendmessaage function but in await ref.doc(time).set(messeges.toJson()); this line it showing me a error of error: The method ‘doc’ isn’t defined for the type ‘Stream’. so plz help me i am new at flutter and stack overflow platform help me.

  static Future<void> sendmessages(chatusres chuser, String msg) async {
    final time = DateTime.now().millisecondsSinceEpoch.toString();
    final Messeges messeges = Messeges(
        fromid: user.uid,
        msg: msg,
        read: '',
        sent: time,
        toid: chuser.id,
        type: '');
    final ref = firestore
        .collection('chats/${getconversationid(user.uid)}/messages}')
        .snapshots();

    await ref.doc(time).set(messeges.toJson());
  }