Add part4

advanced/part4/src/Assets.elm

@@ -0,0 +1,33 @@
+module Assets exposing (error, src)
+
+{-| Assets, such as images, videos, and audio. (We only have images for now.)
+
+We should never expose asset URLs directly; this module should be in charge of
+all of them. One source of truth!
+
+-}
+
+import Html exposing (Attribute, Html)
+import Html.Attributes as Attr
+
+
+type Image
+    = Image String
+
+
+
+-- IMAGES
+
+
+error : Image
+error =
+    Image "/assets/images/error.jpg"
+
+
+
+-- USING IMAGES
+
+
+src : Image -> Attribute msg
+src (Image url) =
+    Attr.src url