diff --git a/package.json b/package.json
index 68d19d0..e03a553 100644
--- a/package.json
+++ b/package.json
@@ -84,7 +84,7 @@
   "license": "ISC",
   "dependencies": {
     "deep-equal": "^1.0.1",
-    "deepcopy": "^1.0.0",
+    "deepcopy": "^2.0.0",
     "promise": "^8.0.1"
   },
   "devDependencies": {
diff --git a/yarn.lock b/yarn.lock
index 3a49faf..9ef1011 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2,80 +2,92 @@
 # yarn lockfile v1
 
 
-"@babel/code-frame@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.0.0-beta.44.tgz#2a02643368de80916162be70865c97774f3adbd9"
+"@babel/code-frame@^7.0.0":
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.0.0.tgz#06e2ab19bdb535385559aabb5ba59729482800f8"
+  integrity sha512-OfC2uemaknXr87bdLUkWog7nYuliM9Ij5HUcajsVcMCpQrcLmtxRbVFTIqmcSkSeYRBFBRxs2FiUqFJDLdiebA==
   dependencies:
-    "@babel/highlight" "7.0.0-beta.44"
+    "@babel/highlight" "^7.0.0"
 
-"@babel/generator@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.0.0-beta.44.tgz#c7e67b9b5284afcf69b309b50d7d37f3e5033d42"
+"@babel/generator@^7.2.2":
+  version "7.3.2"
+  resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.3.2.tgz#fff31a7b2f2f3dad23ef8e01be45b0d5c2fc0132"
+  integrity sha512-f3QCuPppXxtZOEm5GWPra/uYUjmNQlu9pbAD8D/9jze4pTY83rTtB1igTBSwvkeNlC5gR24zFFkz+2WHLFQhqQ==
   dependencies:
-    "@babel/types" "7.0.0-beta.44"
+    "@babel/types" "^7.3.2"
     jsesc "^2.5.1"
-    lodash "^4.2.0"
+    lodash "^4.17.10"
     source-map "^0.5.0"
     trim-right "^1.0.1"
 
-"@babel/helper-function-name@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/helper-function-name/-/helper-function-name-7.0.0-beta.44.tgz#e18552aaae2231100a6e485e03854bc3532d44dd"
+"@babel/helper-function-name@^7.1.0":
+  version "7.1.0"
+  resolved "https://registry.yarnpkg.com/@babel/helper-function-name/-/helper-function-name-7.1.0.tgz#a0ceb01685f73355d4360c1247f582bfafc8ff53"
+  integrity sha512-A95XEoCpb3TO+KZzJ4S/5uW5fNe26DjBGqf1o9ucyLyCmi1dXq/B3c8iaWTfBk3VvetUxl16e8tIrd5teOCfGw==
   dependencies:
-    "@babel/helper-get-function-arity" "7.0.0-beta.44"
-    "@babel/template" "7.0.0-beta.44"
-    "@babel/types" "7.0.0-beta.44"
+    "@babel/helper-get-function-arity" "^7.0.0"
+    "@babel/template" "^7.1.0"
+    "@babel/types" "^7.0.0"
 
-"@babel/helper-get-function-arity@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/helper-get-function-arity/-/helper-get-function-arity-7.0.0-beta.44.tgz#d03ca6dd2b9f7b0b1e6b32c56c72836140db3a15"
+"@babel/helper-get-function-arity@^7.0.0":
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/@babel/helper-get-function-arity/-/helper-get-function-arity-7.0.0.tgz#83572d4320e2a4657263734113c42868b64e49c3"
+  integrity sha512-r2DbJeg4svYvt3HOS74U4eWKsUAMRH01Z1ds1zx8KNTPtpTL5JAsdFv8BNyOpVqdFhHkkRDIg5B4AsxmkjAlmQ==
   dependencies:
-    "@babel/types" "7.0.0-beta.44"
+    "@babel/types" "^7.0.0"
 
-"@babel/helper-split-export-declaration@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/helper-split-export-declaration/-/helper-split-export-declaration-7.0.0-beta.44.tgz#c0b351735e0fbcb3822c8ad8db4e583b05ebd9dc"
+"@babel/helper-split-export-declaration@^7.0.0":
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/@babel/helper-split-export-declaration/-/helper-split-export-declaration-7.0.0.tgz#3aae285c0311c2ab095d997b8c9a94cad547d813"
+  integrity sha512-MXkOJqva62dfC0w85mEf/LucPPS/1+04nmmRMPEBUB++hiiThQ2zPtX/mEWQ3mtzCEjIJvPY8nuwxXtQeQwUag==
   dependencies:
-    "@babel/types" "7.0.0-beta.44"
+    "@babel/types" "^7.0.0"
 
-"@babel/highlight@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/highlight/-/highlight-7.0.0-beta.44.tgz#18c94ce543916a80553edcdcf681890b200747d5"
+"@babel/highlight@^7.0.0":
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/@babel/highlight/-/highlight-7.0.0.tgz#f710c38c8d458e6dd9a201afb637fcb781ce99e4"
+  integrity sha512-UFMC4ZeFC48Tpvj7C8UgLvtkaUuovQX+5xNWrsIoMG8o2z+XFKjKaN9iVmS84dPwVN00W4wPmqvYoZF3EGAsfw==
   dependencies:
     chalk "^2.0.0"
     esutils "^2.0.2"
-    js-tokens "^3.0.0"
-
-"@babel/template@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/template/-/template-7.0.0-beta.44.tgz#f8832f4fdcee5d59bf515e595fc5106c529b394f"
-  dependencies:
-    "@babel/code-frame" "7.0.0-beta.44"
-    "@babel/types" "7.0.0-beta.44"
-    babylon "7.0.0-beta.44"
-    lodash "^4.2.0"
-
-"@babel/traverse@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.0.0-beta.44.tgz#a970a2c45477ad18017e2e465a0606feee0d2966"
-  dependencies:
-    "@babel/code-frame" "7.0.0-beta.44"
-    "@babel/generator" "7.0.0-beta.44"
-    "@babel/helper-function-name" "7.0.0-beta.44"
-    "@babel/helper-split-export-declaration" "7.0.0-beta.44"
-    "@babel/types" "7.0.0-beta.44"
-    babylon "7.0.0-beta.44"
-    debug "^3.1.0"
+    js-tokens "^4.0.0"
+
+"@babel/parser@^7.0.0", "@babel/parser@^7.2.2", "@babel/parser@^7.2.3":
+  version "7.3.2"
+  resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.3.2.tgz#95cdeddfc3992a6ca2a1315191c1679ca32c55cd"
+  integrity sha512-QzNUC2RO1gadg+fs21fi0Uu0OuGNzRKEmgCxoLNzbCdoprLwjfmZwzUrpUNfJPaVRwBpDY47A17yYEGWyRelnQ==
+
+"@babel/template@^7.1.0":
+  version "7.2.2"
+  resolved "https://registry.yarnpkg.com/@babel/template/-/template-7.2.2.tgz#005b3fdf0ed96e88041330379e0da9a708eb2907"
+  integrity sha512-zRL0IMM02AUDwghf5LMSSDEz7sBCO2YnNmpg3uWTZj/v1rcG2BmQUvaGU8GhU8BvfMh1k2KIAYZ7Ji9KXPUg7g==
+  dependencies:
+    "@babel/code-frame" "^7.0.0"
+    "@babel/parser" "^7.2.2"
+    "@babel/types" "^7.2.2"
+
+"@babel/traverse@^7.0.0":
+  version "7.2.3"
+  resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.2.3.tgz#7ff50cefa9c7c0bd2d81231fdac122f3957748d8"
+  integrity sha512-Z31oUD/fJvEWVR0lNZtfgvVt512ForCTNKYcJBGbPb1QZfve4WGH8Wsy7+Mev33/45fhP/hwQtvgusNdcCMgSw==
+  dependencies:
+    "@babel/code-frame" "^7.0.0"
+    "@babel/generator" "^7.2.2"
+    "@babel/helper-function-name" "^7.1.0"
+    "@babel/helper-split-export-declaration" "^7.0.0"
+    "@babel/parser" "^7.2.3"
+    "@babel/types" "^7.2.2"
+    debug "^4.1.0"
     globals "^11.1.0"
-    invariant "^2.2.0"
-    lodash "^4.2.0"
+    lodash "^4.17.10"
 
-"@babel/types@7.0.0-beta.44":
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/@babel/types/-/types-7.0.0-beta.44.tgz#6b1b164591f77dec0a0342aca995f2d046b3a757"
+"@babel/types@^7.0.0", "@babel/types@^7.2.2", "@babel/types@^7.3.2":
+  version "7.3.2"
+  resolved "https://registry.yarnpkg.com/@babel/types/-/types-7.3.2.tgz#424f5be4be633fff33fb83ab8d67e4a8290f5a2f"
+  integrity sha512-3Y6H8xlUlpbGR+XvawiH0UXehqydTmNmEpozWcXymqwcrwYAl5KMvKtQ+TF6f6E08V6Jur7v/ykdDSF+WDEIXQ==
   dependencies:
     esutils "^2.0.2"
-    lodash "^4.2.0"
+    lodash "^4.17.10"
     to-fast-properties "^2.0.0"
 
 "@mrmlnc/readdir-enhanced@^2.2.1":
@@ -510,14 +522,15 @@ babel-core@^6.14.0, babel-core@^6.26.0:
     slash "^1.0.0"
     source-map "^0.5.7"
 
-babel-eslint@^8.2.6:
-  version "8.2.6"
-  resolved "https://registry.yarnpkg.com/babel-eslint/-/babel-eslint-8.2.6.tgz#6270d0c73205628067c0f7ae1693a9e797acefd9"
+babel-eslint@^9.0.0:
+  version "9.0.0"
+  resolved "https://registry.yarnpkg.com/babel-eslint/-/babel-eslint-9.0.0.tgz#7d9445f81ed9f60aff38115f838970df9f2b6220"
+  integrity sha512-itv1MwE3TMbY0QtNfeL7wzak1mV47Uy+n6HtSOO4Xd7rvmO+tsGQSgyOEEgo6Y2vHZKZphaoelNeSVj4vkLA1g==
   dependencies:
-    "@babel/code-frame" "7.0.0-beta.44"
-    "@babel/traverse" "7.0.0-beta.44"
-    "@babel/types" "7.0.0-beta.44"
-    babylon "7.0.0-beta.44"
+    "@babel/code-frame" "^7.0.0"
+    "@babel/parser" "^7.0.0"
+    "@babel/traverse" "^7.0.0"
+    "@babel/types" "^7.0.0"
     eslint-scope "3.7.1"
     eslint-visitor-keys "^1.0.0"
 
@@ -1176,10 +1189,6 @@ babel@^6.14.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel/-/babel-6.23.0.tgz#d0d1e7d803e974765beea3232d4e153c0efb90f4"
 
-babylon@7.0.0-beta.44:
-  version "7.0.0-beta.44"
-  resolved "https://registry.yarnpkg.com/babylon/-/babylon-7.0.0-beta.44.tgz#89159e15e6e30c5096e22d738d8c0af8a0e8ca1d"
-
 babylon@^6.18.0:
   version "6.18.0"
   resolved "https://registry.yarnpkg.com/babylon/-/babylon-6.18.0.tgz#af2f3b88fa6f5c1e4c634d1a0f8eac4f55b395e3"
@@ -1805,6 +1814,13 @@ debug@^2.1.2, debug@^2.2.0, debug@^2.3.3, debug@^2.6.8, debug@^2.6.9:
   dependencies:
     ms "2.0.0"
 
+debug@^4.1.0:
+  version "4.1.1"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-4.1.1.tgz#3b72260255109c6b589cee050f1d516139664791"
+  integrity sha512-pYAIzeRo8J6KPEaJ0VWOh5Pzkbw/RetuzehGM7QRRX5he4fPHx2rdKMB256ehJCkX+XRQm16eZLqLNS8RSZXZw==
+  dependencies:
+    ms "^2.1.1"
+
 debuglog@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/debuglog/-/debuglog-1.0.1.tgz#aa24ffb9ac3df9a2351837cfb2d279360cd78492"
@@ -1848,9 +1864,10 @@ deep-is@~0.1.3:
   version "0.1.3"
   resolved "https://registry.yarnpkg.com/deep-is/-/deep-is-0.1.3.tgz#b369d6fb5dbc13eecf524f91b070feedc357cf34"
 
-deepcopy@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/deepcopy/-/deepcopy-1.0.0.tgz#cea0f3443b3617d2421e066be370cc8126f8959c"
+deepcopy@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/deepcopy/-/deepcopy-2.0.0.tgz#2acb9b7645f9f54d815eee991455e790e72e2252"
+  integrity sha512-d5ZK7pJw7F3k6M5vqDjGiiUS9xliIyWkdzBjnPhnSeRGjkYOGZMCFkdKVwV/WiHOe0NwzB8q+iDo7afvSf0arA==
   dependencies:
     type-detect "^4.0.8"
 
@@ -2962,7 +2979,7 @@ into-stream@^3.1.0:
     from2 "^2.1.1"
     p-is-promise "^1.1.0"
 
-invariant@^2.2.0, invariant@^2.2.2:
+invariant@^2.2.2:
   version "2.2.4"
   resolved "https://registry.yarnpkg.com/invariant/-/invariant-2.2.4.tgz#610f3c92c9359ce1db616e538008d23ff35158e6"
   dependencies:
@@ -3284,14 +3301,14 @@ java-properties@^0.2.9:
   version "0.2.10"
   resolved "https://registry.yarnpkg.com/java-properties/-/java-properties-0.2.10.tgz#2551560c25fa1ad94d998218178f233ad9b18f60"
 
-js-tokens@^3.0.0, js-tokens@^3.0.2:
-  version "3.0.2"
-  resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-3.0.2.tgz#9866df395102130e38f7f996bceb65443209c25b"
-
-"js-tokens@^3.0.0 || ^4.0.0":
+"js-tokens@^3.0.0 || ^4.0.0", js-tokens@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-4.0.0.tgz#19203fb59991df98e3a287050d4647cdeaf32499"
 
+js-tokens@^3.0.2:
+  version "3.0.2"
+  resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-3.0.2.tgz#9866df395102130e38f7f996bceb65443209c25b"
+
 js-yaml@^3.11.0, js-yaml@^3.9.0:
   version "3.12.0"
   resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-3.12.0.tgz#eaed656ec8344f10f527c6bfa1b6e2244de167d1"
@@ -3562,7 +3579,12 @@ lodash.without@~4.4.0:
   version "4.4.0"
   resolved "https://registry.yarnpkg.com/lodash.without/-/lodash.without-4.4.0.tgz#3cd4574a00b67bae373a94b748772640507b7aac"
 
-lodash@^4.17.4, lodash@^4.17.5, lodash@^4.2.0, lodash@^4.2.1, lodash@^4.3.0:
+lodash@^4.17.10:
+  version "4.17.11"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.11.tgz#b39ea6229ef607ecd89e2c8df12536891cac9b8d"
+  integrity sha512-cQKh8igo5QUhZ7lg38DYWAxMvjSAKG0A8wGSVimP07SIUEK2UO+arSRKbRZWtelMtN5V0Hkwh5ryOto/SshYIg==
+
+lodash@^4.17.4, lodash@^4.17.5, lodash@^4.2.1, lodash@^4.3.0:
   version "4.17.10"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.10.tgz#1b7793cf7259ea38fb3661d4d38b3260af8ae4e7"
 
@@ -3870,9 +3892,10 @@ ms@2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.0.0.tgz#5608aeadfc00be6c2901df5f9861788de0d597c8"
 
-ms@^2.0.0:
+ms@^2.0.0, ms@^2.1.1:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.1.tgz#30a5864eb3ebb0a66f2ebe6d727af06a09d86e0a"
+  integrity sha512-tgp+dl5cGk28utYktBsrFqA7HKgrhgPsg6Z/EfhWI4gl1Hwq8B/GmY/0oXZ6nF8hDVesS/FpnYaD/kOWhYQvyg==
 
 mute-stream@0.0.7, mute-stream@~0.0.4:
   version "0.0.7"