Feed stream with changenotifier

lib/models/feed_item.dart

@@ -0,0 +1,16 @@
+class FeedItem {
+  final String text;
+  final DateTime timestamp;
+
+  FeedItem.fromMap(Map<String, dynamic> map)
+      : text = map['text'],
+        timestamp = DateTime.parse(map['timestamp']);
+
+  @override
+  bool operator ==(Object other) {
+    if (other is FeedItem) {
+      return other.timestamp == timestamp;
+    }
+    return false;
+  }
+}