finished ch19 intro

.obsidian/workspace.json

@@ -49,6 +49,20 @@
               "title": "Pattern Matching"
             }
           },
+          {
+            "id": "78cd7043d5d51ffa",
+            "type": "leaf",
+            "state": {
+              "type": "markdown",
+              "state": {
+                "file": "Places Patterns Can Be Used.md",
+                "mode": "source",
+                "source": false
+              },
+              "icon": "lucide-file",
+              "title": "Places Patterns Can Be Used"
+            }
+          },
           {
             "id": "6ed9f182aa3d5f3e",
             "type": "leaf",
@@ -60,7 +74,7 @@
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           }
         ],
-        "currentTab": 2
+        "currentTab": 3
       }
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     "direction": "vertical"
@@ -203,10 +217,11 @@
       "command-palette:Open command palette": false
     }
   },
-  "active": "629d55df46f486d8",
+  "active": "78cd7043d5d51ffa",
   "lastOpenFiles": [
-    "Implementing OO Design Pattern.md",
     "Pattern Matching.md",
+    "Places Patterns Can Be Used.md",
+    "Implementing OO Design Pattern.md",
     "Trait Objects that allow for Values of Different Types.md",
     "Characteristics of OO Languages.md",
     "OOP Programming Features.md",
@@ -230,7 +245,6 @@
     "The Performance Closures and Iterators.md",
     "Improving The IO Project.md",
     "Tests.md",
-    "The Preformance Closures and Iterators.md",
     "minigrep/src/lib.rs",
     "does_not_compile.svg",
     "Untitled.canvas",