Basci atom feed generation

lib/DB/Post.rakumod

@@ -43,6 +43,15 @@ has Bool:D $.hidden is json is rw = False;
 #| document produced it
 method title(--> Str:D) {...}
 
+#| The time the post was last updated at
+method updated(--> DateTime:D) {
+    if @!edited-at {
+        @!edited-at.max
+    } else {
+        $!posted-at
+    }
+}
+
 #| Get the list of slugs for this post, including ones auto generated from
 #| the title, as well as any additional slugs
 method all-slugs(--> Array[Str:D]) {