almost finished ch20.4

.obsidian/workspace.json

@@ -10,20 +10,6 @@
           {
             "id": "de2ac5df5b921166",
             "type": "leaf",
-            "state": {
-              "type": "markdown",
-              "state": {
-                "file": "Advanced Features.md",
-                "mode": "source",
-                "source": false
-              },
-              "icon": "lucide-file",
-              "title": "Advanced Features"
-            }
-          },
-          {
-            "id": "b24fe202609f5b35",
-            "type": "leaf",
             "state": {
               "type": "markdown",
               "state": {
@@ -87,8 +73,7 @@
               "title": "Graph view"
             }
           }
-        ],
-        "currentTab": 1
+        ]
       }
     ],
     "direction": "vertical"
@@ -231,12 +216,13 @@
       "command-palette:Open command palette": false
     }
   },
-  "active": "b24fe202609f5b35",
+  "active": "de2ac5df5b921166",
   "lastOpenFiles": [
     "Advanced Features.md",
-    "Advanced Functions and Closures.md",
     "Advanced Types.md",
     "Advanced Traits.md",
+    "Enums.md",
+    "Advanced Functions and Closures.md",
     "Unsafe Rust.md",
     "Pattern Matching.md",
     "Places Patterns Can Be Used.md",
@@ -258,7 +244,6 @@
     "().md",
     "Smart Pointers.md",
     "Simultaneous Code Running.md",
-    "Passing Data Between Threads.md",
     "minigrep/src/lib.rs",
     "does_not_compile.svg",
     "Untitled.canvas",