diff --git a/chapter1/package-lock.json b/chapter1/package-lock.json
index cbd4b27..fd3a3df 100644
--- a/chapter1/package-lock.json
+++ b/chapter1/package-lock.json
@@ -477,14 +477,21 @@
       "dev": true
     },
     "ajv": {
-      "version": "6.10.0",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.10.0.tgz",
-      "integrity": "sha512-nffhOpkymDECQyR0mnsUtoCE8RlX38G0rYP+wgLWFyZuUyuuojSSvi/+euOiQBIn63whYwYVIIH1TvE3tu4OEg==",
+      "version": "6.12.6",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
+      "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
       "requires": {
-        "fast-deep-equal": "^2.0.1",
+        "fast-deep-equal": "^3.1.1",
         "fast-json-stable-stringify": "^2.0.0",
         "json-schema-traverse": "^0.4.1",
         "uri-js": "^4.2.2"
+      },
+      "dependencies": {
+        "fast-deep-equal": {
+          "version": "3.1.3",
+          "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
+        }
       }
     },
     "ansi-align": {
@@ -2012,11 +2019,6 @@
       "resolved": "https://registry.npmjs.org/extsprintf/-/extsprintf-1.3.0.tgz",
       "integrity": "sha1-lpGEQOMEGnpBT4xS48V06zw+HgU="
     },
-    "fast-deep-equal": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-2.0.1.tgz",
-      "integrity": "sha1-ewUhjd+WZ79/Nwv3/bLLFf3Qqkk="
-    },
     "fast-json-stable-stringify": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz",
@@ -2191,7 +2193,8 @@
         "ansi-regex": {
           "version": "2.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -2212,12 +2215,14 @@
         "balanced-match": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -2232,17 +2237,20 @@
         "code-point-at": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -2359,7 +2367,8 @@
         "inherits": {
           "version": "2.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -2371,6 +2380,7 @@
           "version": "1.0.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -2385,6 +2395,7 @@
           "version": "3.0.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
@@ -2392,12 +2403,14 @@
         "minimist": {
           "version": "0.0.8",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -2416,6 +2429,7 @@
           "version": "0.5.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -2496,7 +2510,8 @@
         "number-is-nan": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -2508,6 +2523,7 @@
           "version": "1.4.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -2593,7 +2609,8 @@
         "safe-buffer": {
           "version": "5.1.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -2629,6 +2646,7 @@
           "version": "1.0.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -2648,6 +2666,7 @@
           "version": "3.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -2691,12 +2710,14 @@
         "wrappy": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
@@ -3558,6 +3579,12 @@
         "jest-util": "^24.3.0"
       }
     },
+    "jest-expect-message": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/jest-expect-message/-/jest-expect-message-1.0.2.tgz",
+      "integrity": "sha512-WFiXMgwS2lOqQZt1iJMI/hOXpUm32X+ApsuzYcQpW5m16Pv6/Gd9kgC+Q+Q1YVNU04kYcAOv9NXMnjg6kKUy6Q==",
+      "dev": true
+    },
     "jest-get-type": {
       "version": "24.3.0",
       "resolved": "https://registry.npmjs.org/jest-get-type/-/jest-get-type-24.3.0.tgz",