diff --git a/package.json b/package.json
index 6d579cd..3d12fdf 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,9 @@
     "deeplearn": "v0.5.1",
     "d3-array": "~1.2.1",
     "d3-format": "~1.2.1",
-    "d3-scale": "~1.0.7"
+    "d3-scale": "~1.0.7",
+    "lodash": "^4.17.13",
+    "mem": "4.0.0"
   },
   "devDependencies": {
     "typescript": "^2.8.3",
diff --git a/yarn.lock b/yarn.lock
index 9c00197..971e82d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3353,6 +3353,11 @@ lodash@^4.17.10, lodash@^4.17.2, lodash@^4.17.3, lodash@^4.17.4, lodash@^4.17.5:
   version "4.17.10"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.10.tgz#1b7793cf7259ea38fb3661d4d38b3260af8ae4e7"
 
+lodash@^4.17.13:
+  version "4.17.15"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
+  integrity sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==
+
 loglevel@^1.4.1:
   version "1.6.1"
   resolved "https://registry.yarnpkg.com/loglevel/-/loglevel-1.6.1.tgz#e0fc95133b6ef276cdc8887cdaf24aa6f156f8fa"
@@ -3399,6 +3404,13 @@ make-dir@^1.0.0:
   dependencies:
     pify "^3.0.0"
 
+map-age-cleaner@^0.1.1:
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/map-age-cleaner/-/map-age-cleaner-0.1.3.tgz#7d583a7306434c055fe474b0f45078e6e1b4b92a"
+  integrity sha512-bJzx6nMoP6PDLPBFmg7+xRKeFZvFboMrGlxmNj9ClvX53KrmvM5bXFXEWjbz4cz1AFn+jWJ9z/DJSz7hrs0w3w==
+  dependencies:
+    p-defer "^1.0.0"
+
 map-cache@^0.2.2:
   version "0.2.2"
   resolved "https://registry.yarnpkg.com/map-cache/-/map-cache-0.2.2.tgz#c32abd0bd6525d9b051645bb4f26ac5dc98a0dbf"
@@ -3432,6 +3444,15 @@ media-typer@0.3.0:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/media-typer/-/media-typer-0.3.0.tgz#8710d7af0aa626f8fffa1ce00168545263255748"
 
+mem@4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/mem/-/mem-4.0.0.tgz#6437690d9471678f6cc83659c00cbafcd6b0cdaf"
+  integrity sha512-WQxG/5xYc3tMbYLXoXPm81ET2WDULiU5FxbuIoNbJqLOOI8zehXFdZuiUEgfdrU2mVB1pxBZUGlYORSrpuJreA==
+  dependencies:
+    map-age-cleaner "^0.1.1"
+    mimic-fn "^1.0.0"
+    p-is-promise "^1.1.0"
+
 mem@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/mem/-/mem-1.1.0.tgz#5edd52b485ca1d900fe64895505399a0dfa45f76"
@@ -3914,10 +3935,20 @@ osenv@^0.1.4:
     os-homedir "^1.0.0"
     os-tmpdir "^1.0.0"
 
+p-defer@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/p-defer/-/p-defer-1.0.0.tgz#9f6eb182f6c9aa8cd743004a7d4f96b196b0fb0c"
+  integrity sha1-n26xgvbJqozXQwBKfU+WsZaw+ww=
+
 p-finally@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/p-finally/-/p-finally-1.0.0.tgz#3fbcfb15b899a44123b34b6dcc18b724336a2cae"
 
+p-is-promise@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/p-is-promise/-/p-is-promise-1.1.0.tgz#9c9456989e9f6588017b0434d56097675c3da05e"
+  integrity sha1-nJRWmJ6fZYgBewQ01WCXZ1w9oF4=
+
 p-limit@^1.0.0, p-limit@^1.1.0:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-1.2.0.tgz#0e92b6bedcb59f022c13d0f1949dc82d15909f1c"