finished ch19.1

.obsidian/workspace.json

@@ -63,6 +63,20 @@
               "title": "Places Patterns Can Be Used"
             }
           },
+          {
+            "id": "7cb3bb4674a93e14",
+            "type": "leaf",
+            "state": {
+              "type": "markdown",
+              "state": {
+                "file": "Refutability.md",
+                "mode": "source",
+                "source": false
+              },
+              "icon": "lucide-file",
+              "title": "Refutability"
+            }
+          },
           {
             "id": "6ed9f182aa3d5f3e",
             "type": "leaf",
@@ -220,6 +234,7 @@
   "active": "78cd7043d5d51ffa",
   "lastOpenFiles": [
     "Pattern Matching.md",
+    "Refutability.md",
     "Places Patterns Can Be Used.md",
     "Implementing OO Design Pattern.md",
     "Trait Objects that allow for Values of Different Types.md",
@@ -244,7 +259,6 @@
     "Reference Counter Smart Pointer.md",
     "The Performance Closures and Iterators.md",
     "Improving The IO Project.md",
-    "Tests.md",
     "minigrep/src/lib.rs",
     "does_not_compile.svg",
     "Untitled.canvas",