diff --git a/_book/package-lock.json b/_book/package-lock.json
index bdcb503..53bcc6e 100644
--- a/_book/package-lock.json
+++ b/_book/package-lock.json
@@ -140,7 +140,7 @@
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           "version": "1.1.3",
-          "resolved": "http://registry.npmjs.org/domelementtype/-/domelementtype-1.1.3.tgz",
+          "resolved": "https://registry.npmjs.org/domelementtype/-/domelementtype-1.1.3.tgz",
           "integrity": "sha1-vSh3PiZCiBrsUVRJJCmcXNgiGFs="
         }
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@@ -221,6 +221,11 @@
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       "integrity": "sha1-FQStJSMVjKpA20onh8sBQRmU6k8="
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+    "function-bind": {
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+      "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.1.tgz",
+      "integrity": "sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A=="
+    },
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       "resolved": "https://registry.npmjs.org/gh-pages/-/gh-pages-2.0.1.tgz",
@@ -281,6 +286,14 @@
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     },
+    "has": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/has/-/has-1.0.3.tgz",
+      "integrity": "sha512-f2dvO0VU6Oej7RkWJGrehjbzMAjFp5/VKPp5tTpWIV4JHHZK1/BxbFRtf/siA2SWTe09caDmVtYYzWEIbBS4zw==",
+      "requires": {
+        "function-bind": "^1.1.1"
+      }
+    },
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       "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-3.0.0.tgz",
@@ -335,9 +348,17 @@
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-      "resolved": "https://registry.npmjs.org/interpret/-/interpret-1.1.0.tgz",
-      "integrity": "sha1-ftGxQQxqDg94z5XTuEQMY/eLhhQ="
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/interpret/-/interpret-1.4.0.tgz",
+      "integrity": "sha512-agE4QfB2Lkp9uICn7BAqoscw4SZP9kTE2hxiFI3jBPmXJfdqiahTbUuKGsMoN2GtqL9AxhYioAcVvgsb1HvRbA=="
+    },
+    "is-core-module": {
+      "version": "2.8.1",
+      "resolved": "https://registry.npmjs.org/is-core-module/-/is-core-module-2.8.1.tgz",
+      "integrity": "sha512-SdNCUs284hr40hFTFP6l0IfZ/RSrMXF3qgoRHd3/79unUTvrFO/JoXwkGm+5J/Oe3E/b5GsnG330uUNgRpu1PA==",
+      "requires": {
+        "has": "^1.0.3"
+      }
     },
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@@ -468,9 +489,9 @@
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-      "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.6.tgz",
-      "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw=="
+      "version": "1.0.7",
+      "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.7.tgz",
+      "integrity": "sha512-LDJzPVEEEPR+y48z93A0Ed0yXb8pAByGWo/k5YYdYgpY2/2EsOsksJrq7lOHxryrVOn1ejG6oAp8ahvOIQD8sw=="
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@@ -513,11 +534,13 @@
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-      "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.8.1.tgz",
-      "integrity": "sha512-AicPrAC7Qu1JxPCZ9ZgCZlY35QgFnNqc+0LtbRNxnVw4TXvjQ72wnuL9JQcEBgXkI9JM8MsT9kaQoHcpCRJOYA==",
+      "version": "1.21.0",
+      "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.21.0.tgz",
+      "integrity": "sha512-3wCbTpk5WJlyE4mSOtDLhqQmGFi0/TD9VPwmiolnk8U0wRgMEktqCXd3vy5buTO3tljvalNvKrjHEfrd2WpEKA==",
       "requires": {
-        "path-parse": "^1.0.5"
+        "is-core-module": "^2.8.0",
+        "path-parse": "^1.0.7",
+        "supports-preserve-symlinks-flag": "^1.0.0"
       }
     },
     "rimraf": {
@@ -534,9 +557,9 @@
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     },
     "shelljs": {
-      "version": "0.8.3",
-      "resolved": "https://registry.npmjs.org/shelljs/-/shelljs-0.8.3.tgz",
-      "integrity": "sha512-fc0BKlAWiLpwZljmOvAOTE/gXawtCoNrP5oaY7KIaQbbyHeQVg01pSEuEGvGh3HEdBU4baCD7wQBwADmM/7f7A==",
+      "version": "0.8.5",
+      "resolved": "https://registry.npmjs.org/shelljs/-/shelljs-0.8.5.tgz",
+      "integrity": "sha512-TiwcRcrkhHvbrZbnRcFYMLl30Dfov3HKqzp5tO5b4pt6G/SezKcYhmDg15zXVBswHmctSAQKznqNW2LO5tTDow==",
       "requires": {
         "glob": "^7.0.0",
         "interpret": "^1.0.0",
@@ -585,6 +608,11 @@
         "has-flag": "^3.0.0"
       }
     },
+    "supports-preserve-symlinks-flag": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/supports-preserve-symlinks-flag/-/supports-preserve-symlinks-flag-1.0.0.tgz",
+      "integrity": "sha512-ot0WnXS9fgdkgIcePe6RHNk1WA8+muPa6cSjeR3V8K27q9BB1rTE3R1p7Hv0z1ZyAc8s6Vvv8DIyWf681MAt0w=="
+    },
     "trim-repeated": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/trim-repeated/-/trim-repeated-1.0.0.tgz",
diff --git a/_book/package.json b/_book/package.json
index 257d6e0..c2342a5 100644
--- a/_book/package.json
+++ b/_book/package.json
@@ -39,6 +39,6 @@
     "gh-pages": "^2.0.1",
     "gitbook-plugin-anchor-navigation-ex": "^1.0.13",
     "moment": "^2.22.2",
-    "shelljs": "^0.8.3"
+    "shelljs": "^0.8.5"
   }
 }