diff --git a/demo/completed-demo/yarn.lock b/demo/completed-demo/yarn.lock
index c662baf..845aed1 100644
--- a/demo/completed-demo/yarn.lock
+++ b/demo/completed-demo/yarn.lock
@@ -194,6 +194,19 @@
     codemirror "~5.53.2"
     react "~16.9.0"
 
+"@jupyterlab/coreutils@^4.0.0", "@jupyterlab/coreutils@^4.3.1":
+  version "4.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/coreutils/-/coreutils-4.3.1.tgz#c0d677946a9c751edc96954998ad08dcadb918a3"
+  integrity sha512-WBwhPmK6VFAjNX7Y6a9JLUiJ2ldURZp/gbN3XsSFEGpZPSgt2UdTRWn60t6UayV1YE9bQy1TS2Pt97/fDDTudQ==
+  dependencies:
+    "@lumino/coreutils" "^1.4.2"
+    "@lumino/disposable" "^1.3.5"
+    "@lumino/signaling" "^1.3.5"
+    minimist "~1.2.0"
+    moment "^2.24.0"
+    path-posix "~1.0.0"
+    url-parse "~1.4.7"
+
 "@jupyterlab/coreutils@^4.2.4":
   version "4.2.4"
   resolved "https://registry.yarnpkg.com/@jupyterlab/coreutils/-/coreutils-4.2.4.tgz#f02ca96f435f94fa049748d2afe0921240fb502d"
@@ -278,6 +291,13 @@
   dependencies:
     "@lumino/coreutils" "^1.4.2"
 
+"@jupyterlab/nbformat@^2.3.1":
+  version "2.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/nbformat/-/nbformat-2.3.1.tgz#a73a6ec2217202fdb8e09df040cd6c8b42d48dd6"
+  integrity sha512-hrMDoiO6Mz7J/19tcXsiboDOQHl/U1KiLhzuueZb2FVLiAe/D0lPHOAD+4H+yfaTrkSwsuej6l67DpZRwUpJBg==
+  dependencies:
+    "@lumino/coreutils" "^1.4.2"
+
 "@jupyterlab/notebook@^2.0.0":
   version "2.2.6"
   resolved "https://registry.yarnpkg.com/@jupyterlab/notebook/-/notebook-2.2.6.tgz#06e180f294079b733d483e1bdf4ab06dcbcab943"
@@ -316,6 +336,17 @@
     "@lumino/messaging" "^1.3.3"
     "@lumino/signaling" "^1.3.5"
 
+"@jupyterlab/observables@^3.3.1":
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/observables/-/observables-3.3.1.tgz#86ce39758944c7d1d67ee641683fa68713f2b893"
+  integrity sha512-Xj9JJMshvKbtnkUp5KE1BU7Hx8LvLDE+syfvbSepZidkYadMPg+bVToLinyyAAtnnZlXvOIGwAcJugHJWbvaaw==
+  dependencies:
+    "@lumino/algorithm" "^1.2.3"
+    "@lumino/coreutils" "^1.4.2"
+    "@lumino/disposable" "^1.3.5"
+    "@lumino/messaging" "^1.3.3"
+    "@lumino/signaling" "^1.3.5"
+
 "@jupyterlab/outputarea@^2.2.3":
   version "2.2.3"
   resolved "https://registry.yarnpkg.com/@jupyterlab/outputarea/-/outputarea-2.2.3.tgz#1be7a190a060234b9fb684f5bcfdbc283739da40"
@@ -363,6 +394,24 @@
     lodash.escape "^4.0.1"
     marked "^0.8.0"
 
+"@jupyterlab/services@^5.0.0":
+  version "5.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/services/-/services-5.3.1.tgz#5f6a3dd90347b7d0a4d6d3335ae20f296640d744"
+  integrity sha512-bV3UVihpeX5W5V57xLoL8gK0PVkvBeiSmHIlFEL2S8rCCDWLcyed7PoLnTe9eRvbCBZpZOEyqs9tk1zlQkQwqQ==
+  dependencies:
+    "@jupyterlab/coreutils" "^4.3.1"
+    "@jupyterlab/nbformat" "^2.3.1"
+    "@jupyterlab/observables" "^3.3.1"
+    "@jupyterlab/settingregistry" "^2.3.1"
+    "@jupyterlab/statedb" "^2.3.1"
+    "@lumino/algorithm" "^1.2.3"
+    "@lumino/coreutils" "^1.4.2"
+    "@lumino/disposable" "^1.3.5"
+    "@lumino/polling" "^1.1.1"
+    "@lumino/signaling" "^1.3.5"
+    node-fetch "^2.6.0"
+    ws "^7.2.0"
+
 "@jupyterlab/services@^5.2.4":
   version "5.2.4"
   resolved "https://registry.yarnpkg.com/@jupyterlab/services/-/services-5.2.4.tgz#e9331a98db435abc83ffa902799df59fe6b9c15c"
@@ -394,6 +443,19 @@
     ajv "^6.10.2"
     json5 "^2.1.1"
 
+"@jupyterlab/settingregistry@^2.3.1":
+  version "2.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/settingregistry/-/settingregistry-2.3.1.tgz#9821f3462285f82efdf8d7214b9ae60f3969ecbf"
+  integrity sha512-UeZObQ6pMkca1SSYzrmPKGwiRZdm6yuBf1Ab8Cv4cGBzVplFmUp8kHjbK/V+PSV9nhog/qlpUREHoy4jlMFxUA==
+  dependencies:
+    "@jupyterlab/statedb" "^2.3.1"
+    "@lumino/commands" "^1.10.1"
+    "@lumino/coreutils" "^1.4.2"
+    "@lumino/disposable" "^1.3.5"
+    "@lumino/signaling" "^1.3.5"
+    ajv "^6.10.2"
+    json5 "^2.1.1"
+
 "@jupyterlab/statedb@^2.2.4":
   version "2.2.4"
   resolved "https://registry.yarnpkg.com/@jupyterlab/statedb/-/statedb-2.2.4.tgz#674d7b59b51c6b2f76e8557eb2ff64797f9a85e9"
@@ -405,6 +467,17 @@
     "@lumino/properties" "^1.1.6"
     "@lumino/signaling" "^1.3.5"
 
+"@jupyterlab/statedb@^2.3.1":
+  version "2.3.1"
+  resolved "https://registry.yarnpkg.com/@jupyterlab/statedb/-/statedb-2.3.1.tgz#c6a04d2c2f6c45a3e62a276e0cbe06a3fcb36d83"
+  integrity sha512-4f4hgSFg08sTIQjXlVOv93EGMAVxFOrZ4pk3RTyxnptfBboTvX/h9AmqE6REaNxi1KMwCXMeVO9gO+CFlFnFdA==
+  dependencies:
+    "@lumino/commands" "^1.10.1"
+    "@lumino/coreutils" "^1.4.2"
+    "@lumino/disposable" "^1.3.5"
+    "@lumino/properties" "^1.1.6"
+    "@lumino/signaling" "^1.3.5"
+
 "@jupyterlab/statusbar@^2.2.3":
   version "2.2.3"
   resolved "https://registry.yarnpkg.com/@jupyterlab/statusbar/-/statusbar-2.2.3.tgz#27f65e4e6303732f4eb56d1d8d1486d55f0dc68a"
@@ -1509,9 +1582,11 @@ nice-try@^1.0.4:
   integrity sha512-1nh45deeb5olNY7eX82BkPO7SSxR5SSYJiPTrTdFUVYwAl8CKMA5N9PjTYkHiRjisVcxcQ1HXdLhx2qxxJzLNQ==
 
 node-fetch@^2.6.0:
-  version "2.6.1"
-  resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.1.tgz#045bd323631f76ed2e2b55573394416b639a0052"
-  integrity sha512-V4aYg89jEoVRxRb2fJdAg8FHvI7cEyYdVAh94HH0UIK8oJxUfkjlDQN9RbMx+bEjP7+ggMiFRprSti032Oipxw==
+  version "2.6.7"
+  resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.7.tgz#24de9fba827e3b4ae44dc8b20256a379160052ad"
+  integrity sha512-ZjMPFEfVx5j+y2yF35Kzx5sF7kDzxuDj6ziH4FFbOp87zKDZNx8yExJIb05OGF4Nlt9IHFIMBkRl41VdvcNdbQ==
+  dependencies:
+    whatwg-url "^5.0.0"
 
 normalize.css@^8.0.1:
   version "8.0.1"
@@ -1998,6 +2073,11 @@ tmp@^0.0.33:
   dependencies:
     os-tmpdir "~1.0.2"
 
+tr46@~0.0.3:
+  version "0.0.3"
+  resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
+  integrity sha512-N3WMsuqV66lT30CrXNbEjx4GEwlow3v6rr4mCcv6prnfwhS01rkgyFdjPNBYd9br7LpXV1+Emh01fHnq2Gdgrw==
+
 tslib@^1.8.1, tslib@^1.9.0, tslib@~1.13.0:
   version "1.13.0"
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.13.0.tgz#c881e13cc7015894ed914862d276436fa9a47043"
@@ -2077,6 +2157,19 @@ warning@^4.0.2, warning@^4.0.3:
   dependencies:
     loose-envify "^1.0.0"
 
+webidl-conversions@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/webidl-conversions/-/webidl-conversions-3.0.1.tgz#24534275e2a7bc6be7bc86611cc16ae0a5654871"
+  integrity sha512-2JAn3z8AR6rjK8Sm8orRC0h/bcl/DqL7tRPdGZ4I1CjdF+EaMLmYxBHyXuKL849eucPFhvBoxMsflfOb8kxaeQ==
+
+whatwg-url@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/whatwg-url/-/whatwg-url-5.0.0.tgz#966454e8765462e37644d3626f6742ce8b70965d"
+  integrity sha512-saE57nupxk6v3HY35+jzBwYa0rKSy0XR8JSxZPwgLr7ys0IBzhGviA1/TUGJLmSVqs8pb9AnvICXEuOHLprYTw==
+  dependencies:
+    tr46 "~0.0.3"
+    webidl-conversions "^3.0.0"
+
 which@^1.2.9:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/which/-/which-1.3.1.tgz#a45043d54f5805316da8d62f9f50918d3da70b0a"