diff --git a/package.json b/package.json
index 4fb1a18..5578567 100644
--- a/package.json
+++ b/package.json
@@ -34,10 +34,10 @@
     "@aureooms/js-compare": "1.4.8",
     "@aureooms/js-functools": "2.0.3",
     "@aureooms/js-itertools": "4.1.0",
-    "@babel/cli": "7.12.13",
-    "@babel/core": "7.12.13",
+    "@babel/cli": "7.12.16",
+    "@babel/core": "7.12.16",
     "@babel/polyfill": "7.12.1",
-    "@babel/preset-env": "7.12.13",
+    "@babel/preset-env": "7.12.16",
     "@babel/register": "7.12.13",
     "ava": "3.15.0",
     "coveralls": "3.1.0",
diff --git a/yarn.lock b/yarn.lock
index 2a237b2..4f8c1b7 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -42,10 +42,10 @@
   resolved "https://registry.yarnpkg.com/@aureooms/js-mapping/-/js-mapping-4.0.0.tgz#ae83268a6b4e6ae7d4b1ff185bd2416c34e2064e"
   integrity sha512-zSs5uEBlosLwG2MWiHdCKounMQ84AG5RXrmKiA9g1QrErOu6quQZu2dZp5gbG0pS0cS2V9H/txJnuMw54hhtEw==
 
-"@babel/cli@7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/cli/-/cli-7.12.13.tgz#ae2c6a75fa43f3db4bca0659799b0dfca3f5212b"
-  integrity sha512-Zto3HPeE0GRmaxobUl7NvFTo97NKe1zdAuWqTO8oka7nE0IIqZ4CFvuRZe1qf+ZMd7eHMhwqrecjwc10mjXo/g==
+"@babel/cli@7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/cli/-/cli-7.12.16.tgz#bde5bc5118d90e539603abcd37938c5f0fd6c87a"
+  integrity sha512-cKWkNCxbpjSuYLbdeJs4kOnyW1E2D65pu7SodXDOkzahIN/wSgT8geIqf6+pJTgCo47zrOMGcJTmjSFe5WKYwQ==
   dependencies:
     commander "^4.0.1"
     convert-source-map "^1.1.0"
@@ -78,16 +78,16 @@
   resolved "https://registry.yarnpkg.com/@babel/compat-data/-/compat-data-7.12.13.tgz#27e19e0ed3726ccf54067ced4109501765e7e2e8"
   integrity sha512-U/hshG5R+SIoW7HVWIdmy1cB7s3ki+r3FpyEZiCgpi4tFgPnX/vynY80ZGSASOIrUM6O7VxOgCZgdt7h97bUGg==
 
-"@babel/core@7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/core/-/core-7.12.13.tgz#b73a87a3a3e7d142a66248bf6ad88b9ceb093425"
-  integrity sha512-BQKE9kXkPlXHPeqissfxo0lySWJcYdEP0hdtJOH/iJfDdhOCcgtNCjftCJg3qqauB4h+lz2N6ixM++b9DN1Tcw==
+"@babel/core@7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/core/-/core-7.12.16.tgz#8c6ba456b23b680a6493ddcfcd9d3c3ad51cab7c"
+  integrity sha512-t/hHIB504wWceOeaOoONOhu+gX+hpjfeN6YRBT209X/4sibZQfSF1I0HFRRlBe97UZZosGx5XwUg1ZgNbelmNw==
   dependencies:
     "@babel/code-frame" "^7.12.13"
-    "@babel/generator" "^7.12.13"
+    "@babel/generator" "^7.12.15"
     "@babel/helper-module-transforms" "^7.12.13"
     "@babel/helpers" "^7.12.13"
-    "@babel/parser" "^7.12.13"
+    "@babel/parser" "^7.12.16"
     "@babel/template" "^7.12.13"
     "@babel/traverse" "^7.12.13"
     "@babel/types" "^7.12.13"
@@ -130,6 +130,15 @@
     jsesc "^2.5.1"
     source-map "^0.5.0"
 
+"@babel/generator@^7.12.15":
+  version "7.12.15"
+  resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.12.15.tgz#4617b5d0b25cc572474cc1aafee1edeaf9b5368f"
+  integrity sha512-6F2xHxBiFXWNSGb7vyCUTBF8RCLY66rS0zEPcP8t/nQyXjha5EuK4z7H5o7fWG8B4M7y6mqVWq1J+1PuwRhecQ==
+  dependencies:
+    "@babel/types" "^7.12.13"
+    jsesc "^2.5.1"
+    source-map "^0.5.0"
+
 "@babel/generator@^7.9.0", "@babel/generator@^7.9.5":
   version "7.9.5"
   resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.9.5.tgz#27f0917741acc41e6eaaced6d68f96c3fa9afaf9"
@@ -162,13 +171,13 @@
     "@babel/helper-explode-assignable-expression" "^7.12.13"
     "@babel/types" "^7.12.13"
 
-"@babel/helper-compilation-targets@^7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/helper-compilation-targets/-/helper-compilation-targets-7.12.13.tgz#d689cdef88810aa74e15a7a94186f26a3d773c98"
-  integrity sha512-dXof20y/6wB5HnLOGyLh/gobsMvDNoekcC+8MCV2iaTd5JemhFkPD73QB+tK3iFC9P0xJC73B6MvKkyUfS9cCw==
+"@babel/helper-compilation-targets@^7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/helper-compilation-targets/-/helper-compilation-targets-7.12.16.tgz#6905238b4a5e02ba2d032c1a49dd1820fe8ce61b"
+  integrity sha512-dBHNEEaZx7F3KoUYqagIhRIeqyyuI65xMndMZ3WwGwEBI609I4TleYQHcrS627vbKyNTXqShoN+fvYD9HuQxAg==
   dependencies:
     "@babel/compat-data" "^7.12.13"
-    "@babel/helper-validator-option" "^7.12.11"
+    "@babel/helper-validator-option" "^7.12.16"
     browserslist "^4.14.5"
     semver "^5.5.0"
 
@@ -418,10 +427,10 @@
   resolved "https://registry.yarnpkg.com/@babel/helper-validator-identifier/-/helper-validator-identifier-7.9.5.tgz#90977a8e6fbf6b431a7dc31752eee233bf052d80"
   integrity sha512-/8arLKUFq882w4tWGj9JYzRpAlZgiWUJ+dtteNTDqrRBz9Iguck9Rn3ykuBDoUwh2TO4tSAJlrxDUOXWklJe4g==
 
-"@babel/helper-validator-option@^7.12.11":
-  version "7.12.11"
-  resolved "https://registry.yarnpkg.com/@babel/helper-validator-option/-/helper-validator-option-7.12.11.tgz#d66cb8b7a3e7fe4c6962b32020a131ecf0847f4f"
-  integrity sha512-TBFCyj939mFSdeX7U7DDj32WtzYY7fDcalgq8v3fBZMNOJQNn7nOYzMaUCiPxPYfCup69mtIpqlKgMZLvQ8Xhw==
+"@babel/helper-validator-option@^7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/helper-validator-option/-/helper-validator-option-7.12.16.tgz#f73cbd3bbba51915216c5dea908e9b206bb10051"
+  integrity sha512-uCgsDBPUQDvzr11ePPo4TVEocxj8RXjUVSC/Y8N1YpVAI/XDdUwGJu78xmlGhTxj2ntaWM7n9LQdRtyhOzT2YQ==
 
 "@babel/helper-wrap-function@^7.12.13":
   version "7.12.13"
@@ -474,6 +483,11 @@
   resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.12.13.tgz#3ee7be4131fe657ba9143d5c5b3a9f253fdb75e9"
   integrity sha512-z7n7ybOUzaRc3wwqLpAX8UFIXsrVXUJhtNGBwAnLz6d1KUapqyq7ad2La8gZ6CXhHmGAIL32cop8Tst4/PNWLw==
 
+"@babel/parser@^7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.12.16.tgz#cc31257419d2c3189d394081635703f549fc1ed4"
+  integrity sha512-c/+u9cqV6F0+4Hpq01jnJO+GLp2DdT63ppz9Xa+6cHaajM9VFzK/iDXiKK65YtpeVwu+ctfS6iqlMqRgQRzeCw==
+
 "@babel/parser@^7.7.5", "@babel/parser@^7.8.6", "@babel/parser@^7.9.0":
   version "7.9.4"
   resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.9.4.tgz#68a35e6b0319bbc014465be43828300113f2f2e8"
@@ -496,12 +510,12 @@
     "@babel/helper-create-class-features-plugin" "^7.12.13"
     "@babel/helper-plugin-utils" "^7.12.13"
 
-"@babel/plugin-proposal-dynamic-import@^7.12.1":
-  version "7.12.1"
-  resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-dynamic-import/-/plugin-proposal-dynamic-import-7.12.1.tgz#43eb5c2a3487ecd98c5c8ea8b5fdb69a2749b2dc"
-  integrity sha512-a4rhUSZFuq5W8/OO8H7BL5zspjnc1FLd9hlOxIK/f7qG4a0qsqk8uvF/ywgBA8/OmjsapjpvaEOYItfGG1qIvQ==
+"@babel/plugin-proposal-dynamic-import@^7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-dynamic-import/-/plugin-proposal-dynamic-import-7.12.16.tgz#b9f33b252e3406d492a15a799c9d45a9a9613473"
+  integrity sha512-yiDkYFapVxNOCcBfLnsb/qdsliroM+vc3LHiZwS4gh7pFjo5Xq3BDhYBNn3H3ao+hWPvqeeTdU+s+FIvokov+w==
   dependencies:
-    "@babel/helper-plugin-utils" "^7.10.4"
+    "@babel/helper-plugin-utils" "^7.12.13"
     "@babel/plugin-syntax-dynamic-import" "^7.8.0"
 
 "@babel/plugin-proposal-export-namespace-from@^7.12.13":
@@ -561,10 +575,10 @@
     "@babel/helper-plugin-utils" "^7.12.13"
     "@babel/plugin-syntax-optional-catch-binding" "^7.8.0"
 
-"@babel/plugin-proposal-optional-chaining@^7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-optional-chaining/-/plugin-proposal-optional-chaining-7.12.13.tgz#63a7d805bc8ce626f3234ee5421a2a7fb23f66d9"
-  integrity sha512-0ZwjGfTcnZqyV3y9DSD1Yk3ebp+sIUpT2YDqP8hovzaNZnQq2Kd7PEqa6iOIUDBXBt7Jl3P7YAcEIL5Pz8u09Q==
+"@babel/plugin-proposal-optional-chaining@^7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-optional-chaining/-/plugin-proposal-optional-chaining-7.12.16.tgz#600c7531f754186b0f2096e495a92da7d88aa139"
+  integrity sha512-O3ohPwOhkwji5Mckb7F/PJpJVJY3DpPsrt/F0Bk40+QMk9QpAIqeGusHWqu/mYqsM8oBa6TziL/2mbERWsUZjg==
   dependencies:
     "@babel/helper-plugin-utils" "^7.12.13"
     "@babel/helper-skip-transparent-expression-wrappers" "^7.12.1"
@@ -942,19 +956,19 @@
     core-js "^2.6.5"
     regenerator-runtime "^0.13.4"
 
-"@babel/preset-env@7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/preset-env/-/preset-env-7.12.13.tgz#3aa2d09cf7d255177538dff292ac9af29ad46525"
-  integrity sha512-JUVlizG8SoFTz4LmVUL8++aVwzwxcvey3N0j1tRbMAXVEy95uQ/cnEkmEKHN00Bwq4voAV3imQGnQvpkLAxsrw==
+"@babel/preset-env@7.12.16":
+  version "7.12.16"
+  resolved "https://registry.yarnpkg.com/@babel/preset-env/-/preset-env-7.12.16.tgz#16710e3490e37764b2f41886de0a33bc4ae91082"
+  integrity sha512-BXCAXy8RE/TzX416pD2hsVdkWo0G+tYd16pwnRV4Sc0fRwTLRS/Ssv8G5RLXUGQv7g4FG7TXkdDJxCjQ5I+Zjg==
   dependencies:
     "@babel/compat-data" "^7.12.13"
-    "@babel/helper-compilation-targets" "^7.12.13"
+    "@babel/helper-compilation-targets" "^7.12.16"
     "@babel/helper-module-imports" "^7.12.13"
     "@babel/helper-plugin-utils" "^7.12.13"
-    "@babel/helper-validator-option" "^7.12.11"
+    "@babel/helper-validator-option" "^7.12.16"
     "@babel/plugin-proposal-async-generator-functions" "^7.12.13"
     "@babel/plugin-proposal-class-properties" "^7.12.13"
-    "@babel/plugin-proposal-dynamic-import" "^7.12.1"
+    "@babel/plugin-proposal-dynamic-import" "^7.12.16"
     "@babel/plugin-proposal-export-namespace-from" "^7.12.13"
     "@babel/plugin-proposal-json-strings" "^7.12.13"
     "@babel/plugin-proposal-logical-assignment-operators" "^7.12.13"
@@ -962,7 +976,7 @@
     "@babel/plugin-proposal-numeric-separator" "^7.12.13"
     "@babel/plugin-proposal-object-rest-spread" "^7.12.13"
     "@babel/plugin-proposal-optional-catch-binding" "^7.12.13"
-    "@babel/plugin-proposal-optional-chaining" "^7.12.13"
+    "@babel/plugin-proposal-optional-chaining" "^7.12.16"
     "@babel/plugin-proposal-private-methods" "^7.12.13"
     "@babel/plugin-proposal-unicode-property-regex" "^7.12.13"
     "@babel/plugin-syntax-async-generators" "^7.8.0"