diff --git a/.gitignore b/.gitignore
index 03d510f..4fe8fa4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,15 +1,17 @@
+**/*~
+/_*/
 .bundle
-vendor/bundle
-node_modules
 *.docx
 *.epub
-/_*/
-**/*~
-*.pdf
-*.zip
-\.vagrant
-tmp*
 /images/*.circo.svg
 /images/*.dot.svg
 /images/*.ora.png
 /images/*.uml.svg
+.marp/*.css
+node_modules
+*.pdf
+.sass-cache
+tmp*
+\.vagrant
+vendor/bundle
+*.zip
diff --git a/.marp/Makefile b/.marp/Makefile
index ac5522e..c87d09c 100644
--- a/.marp/Makefile
+++ b/.marp/Makefile
@@ -1,11 +1,12 @@
 
 all: build
 
-
 build: theme.css
 
 %.css: %.scss
-	cd .. && npx node-sass --output-style compressed .marp/$< > .marp/$@
+	cd .. \
+		&& npx node-sass --output-style compressed .marp/$< > .marp/$@ \
+		|| ( rm -f .marp/$@ && exit 1 )
 
 .PHONY: build
 
diff --git a/.tool-versions b/.tool-versions
new file mode 100644
index 0000000..52d1c3e
--- /dev/null
+++ b/.tool-versions
@@ -0,0 +1 @@
+python 3.8.0
diff --git a/Makefile b/Makefile
index f6c8459..10016fe 100755
--- a/Makefile
+++ b/Makefile
@@ -84,13 +84,16 @@ images: $(DOCS_IMAGES_SVG) $(DOCS_IMAGES_PNG) ## build images
 %.circo.svg: %.circo
 	circo -Tsvg $< > $@
 
+.marp/theme.css:
+	cd .marp && $(MAKE) theme.css
+
 watch: ## run development server
 	pipenv run honcho start 
 
 watch-docs-internal:
 	pipenv run mkdocs serve --dev-addr 0.0.0.0:$(DOCS_PORT)
 
-watch-slides-internal:
+watch-slides-internal: .marp/theme.css
 	PORT=$(SLIDES_PORT) \
 		 npx marp \
 		 --engine $$(pwd)/.marp/engine.js \
diff --git a/Pipfile b/Pipfile
index 2922272..b477a86 100644
--- a/Pipfile
+++ b/Pipfile
@@ -12,6 +12,7 @@ mdx-truly-sane-lists = "*"
 pymdown-extensions = "*"
 honcho = "*"
 pyinotify = "*"
+mkdocs-gitbook = "*"
 
 [requires]
 python_full_version = "3.8.3"
diff --git a/Pipfile.lock b/Pipfile.lock
index 466eaeb..1934c7d 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "0105843210a4f22c0f8d167e6341a0aad111b8aba24f27de5b640fa22eb228b5"
+            "sha256": "545d3115bc32a7fc35ee3c62f87a5cc727fa23d0908a2a1db960739e0650ca4c"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -39,17 +39,17 @@
         },
         "jinja2": {
             "hashes": [
-                "sha256:89aab215427ef59c34ad58735269eb58b1a5808103067f7bb9d5836c651b3bb0",
-                "sha256:f0a4641d3cf955324a89c04f3d94663aa4d638abe8f733ecd3582848e1c37035"
+                "sha256:03e47ad063331dd6a3f04a43eddca8a966a26ba0c5b7207a9a9e4e08f1b29419",
+                "sha256:a6d58433de0ae800347cab1fa3043cebbabe8baa9d29e668f1c768cb87a333c6"
             ],
-            "version": "==2.11.2"
+            "version": "==2.11.3"
         },
         "joblib": {
             "hashes": [
-                "sha256:8f52bf24c64b608bf0b2563e0e47d6fcf516abc8cfafe10cfd98ad66d94f92d6",
-                "sha256:d348c5d4ae31496b2aa060d6d9b787864dd204f9480baaa52d18850cb43e9f49"
+                "sha256:9c17567692206d2f3fb9ecf5e991084254fe631665c450b443761c4186a613f7",
+                "sha256:feeb1ec69c4d45129954f1b7034954241eedfd6ba39b5e9e4b6883be3332d5e5"
             ],
-            "version": "==0.16.0"
+            "version": "==1.0.1"
         },
         "livereload": {
             "hashes": [
@@ -69,10 +69,10 @@
         },
         "markdown": {
             "hashes": [
-                "sha256:1fafe3f1ecabfb514a5285fca634a53c1b32a81cb0feb154264d55bf2ff22c17",
-                "sha256:c467cd6233885534bf0fe96e62e3cf46cfc1605112356c4f9981512b8174de59"
+                "sha256:31b5b491868dcc87d6c24b7e3d19a0d730d59d3e46f4eea6430a321bed387a49",
+                "sha256:96c3ba1261de2f7547b46a00ea8463832c921d3f9d6aba3f255a6f71386db20c"
             ],
-            "version": "==3.2.2"
+            "version": "==3.3.4"
         },
         "markupsafe": {
             "hashes": [
@@ -81,8 +81,12 @@
                 "sha256:09c4b7f37d6c648cb13f9230d847adf22f8171b1ccc4d5682398e77f40309235",
                 "sha256:1027c282dad077d0bae18be6794e6b6b8c91d58ed8a8d89a89d59693b9131db5",
                 "sha256:13d3144e1e340870b25e7b10b98d779608c02016d5184cfb9927a9f10c689f42",
+                "sha256:195d7d2c4fbb0ee8139a6cf67194f3973a6b3042d742ebe0a9ed36d8b6f0c07f",
+                "sha256:22c178a091fc6630d0d045bdb5992d2dfe14e3259760e713c490da5323866c39",
                 "sha256:24982cc2533820871eba85ba648cd53d8623687ff11cbb805be4ff7b4c971aff",
                 "sha256:29872e92839765e546828bb7754a68c418d927cd064fd4708fab9fe9c8bb116b",
+                "sha256:2beec1e0de6924ea551859edb9e7679da6e4870d32cb766240ce17e0a0ba2014",
+                "sha256:3b8a6499709d29c2e2399569d96719a1b21dcd94410a586a18526b143ec8470f",
                 "sha256:43a55c2930bbc139570ac2452adf3d70cdbb3cfe5912c71cdce1c2c6bbd9c5d1",
                 "sha256:46c99d2de99945ec5cb54f23c8cd5689f6d7177305ebff350a58ce5f8de1669e",
                 "sha256:500d4957e52ddc3351cabf489e79c91c17f6e0899158447047588650b5e69183",
@@ -91,24 +95,39 @@
                 "sha256:62fe6c95e3ec8a7fad637b7f3d372c15ec1caa01ab47926cfdf7a75b40e0eac1",
                 "sha256:6788b695d50a51edb699cb55e35487e430fa21f1ed838122d722e0ff0ac5ba15",
                 "sha256:6dd73240d2af64df90aa7c4e7481e23825ea70af4b4922f8ede5b9e35f78a3b1",
+                "sha256:6f1e273a344928347c1290119b493a1f0303c52f5a5eae5f16d74f48c15d4a85",
+                "sha256:6fffc775d90dcc9aed1b89219549b329a9250d918fd0b8fa8d93d154918422e1",
                 "sha256:717ba8fe3ae9cc0006d7c451f0bb265ee07739daf76355d06366154ee68d221e",
                 "sha256:79855e1c5b8da654cf486b830bd42c06e8780cea587384cf6545b7d9ac013a0b",
                 "sha256:7c1699dfe0cf8ff607dbdcc1e9b9af1755371f92a68f706051cc8c37d447c905",
+                "sha256:7fed13866cf14bba33e7176717346713881f56d9d2bcebab207f7a036f41b850",
+                "sha256:84dee80c15f1b560d55bcfe6d47b27d070b4681c699c572af2e3c7cc90a3b8e0",
                 "sha256:88e5fcfb52ee7b911e8bb6d6aa2fd21fbecc674eadd44118a9cc3863f938e735",
                 "sha256:8defac2f2ccd6805ebf65f5eeb132adcf2ab57aa11fdf4c0dd5169a004710e7d",
+                "sha256:98bae9582248d6cf62321dcb52aaf5d9adf0bad3b40582925ef7c7f0ed85fceb",
                 "sha256:98c7086708b163d425c67c7a91bad6e466bb99d797aa64f965e9d25c12111a5e",
                 "sha256:9add70b36c5666a2ed02b43b335fe19002ee5235efd4b8a89bfcf9005bebac0d",
                 "sha256:9bf40443012702a1d2070043cb6291650a0841ece432556f784f004937f0f32c",
+                "sha256:a6a744282b7718a2a62d2ed9d993cad6f5f585605ad352c11de459f4108df0a1",
+                "sha256:acf08ac40292838b3cbbb06cfe9b2cb9ec78fce8baca31ddb87aaac2e2dc3bc2",
                 "sha256:ade5e387d2ad0d7ebf59146cc00c8044acbd863725f887353a10df825fc8ae21",
                 "sha256:b00c1de48212e4cc9603895652c5c410df699856a2853135b3967591e4beebc2",
                 "sha256:b1282f8c00509d99fef04d8ba936b156d419be841854fe901d8ae224c59f0be5",
+                "sha256:b1dba4527182c95a0db8b6060cc98ac49b9e2f5e64320e2b56e47cb2831978c7",
                 "sha256:b2051432115498d3562c084a49bba65d97cf251f5a331c64a12ee7e04dacc51b",
+                "sha256:b7d644ddb4dbd407d31ffb699f1d140bc35478da613b441c582aeb7c43838dd8",
                 "sha256:ba59edeaa2fc6114428f1637ffff42da1e311e29382d81b339c1817d37ec93c6",
+                "sha256:bf5aa3cbcfdf57fa2ee9cd1822c862ef23037f5c832ad09cfea57fa846dec193",
                 "sha256:c8716a48d94b06bb3b2524c2b77e055fb313aeb4ea620c8dd03a105574ba704f",
+                "sha256:caabedc8323f1e93231b52fc32bdcde6db817623d33e100708d9a68e1f53b26b",
                 "sha256:cd5df75523866410809ca100dc9681e301e3c27567cf498077e8551b6d20e42f",
                 "sha256:cdb132fc825c38e1aeec2c8aa9338310d29d337bebbd7baa06889d09a60a1fa2",
+                "sha256:d53bc011414228441014aa71dbec320c66468c1030aae3a6e29778a3382d96e5",
+                "sha256:d73a845f227b0bfe8a7455ee623525ee656a9e2e749e4742706d80a6065d5e2c",
+                "sha256:d9be0ba6c527163cbed5e0857c451fcd092ce83947944d6c14bc95441203f032",
                 "sha256:e249096428b3ae81b08327a63a485ad0878de3fb939049038579ac0ef61e17e7",
-                "sha256:e8313f01ba26fbbe36c7be1966a7b7424942f670f38e666995b88d012765b9be"
+                "sha256:e8313f01ba26fbbe36c7be1966a7b7424942f670f38e666995b88d012765b9be",
+                "sha256:feb7b34d6325451ef96bc0e36e1a6c0c1c64bc1fbec4b854f4529e51887b1621"
             ],
             "version": "==1.1.1"
         },
@@ -128,13 +147,21 @@
             "index": "pypi",
             "version": "==1.1.2"
         },
-        "mkdocs-material": {
+        "mkdocs-gitbook": {
             "hashes": [
-                "sha256:79bf2951e5b9d435b8e1c0c3340a642f8359d90656b9344e64d9a2b7b6d2a1bb",
-                "sha256:8facb50db21fc0152ea5459ef67298512370503816dd2a6a2887f67330f61ed2"
+                "sha256:c094f9d77e47d54379a0d3816097b56511e760fedb23dcf89bc925f6ac4e75f3",
+                "sha256:e929c3caf655076eaa030128cfd104687b9ec14644d54f4a175d43e13ac60ef8"
             ],
             "index": "pypi",
-            "version": "==6.0.1"
+            "version": "==0.0.1"
+        },
+        "mkdocs-material": {
+            "hashes": [
+                "sha256:1798d9a0a01f54db575801826d6b1b99a1185fef58bcaca36625ee1d519df83c",
+                "sha256:925221cf1877a50f72d9bf64a7a26c407d4b14fdc6a16e27fe7547178613e56c"
+            ],
+            "index": "pypi",
+            "version": "==7.1.1"
         },
         "mkdocs-material-extensions": {
             "hashes": [
@@ -145,16 +172,17 @@
         },
         "nltk": {
             "hashes": [
-                "sha256:845365449cd8c5f9731f7cb9f8bd6fd0767553b9d53af9eb1b3abf7700936b35"
+                "sha256:1235660f52ab10fda34d5277096724747f767b2903e1c0c4e14bde013552c9ba",
+                "sha256:cbc2ed576998fcf7cd181eeb3ca029e5f0025b264074b4beb57ce780673f8b86"
             ],
-            "version": "==3.5"
+            "version": "==3.6.1"
         },
         "pygments": {
             "hashes": [
-                "sha256:307543fe65c0947b126e83dd5a61bd8acbd84abec11f43caebaf5534cbc17998",
-                "sha256:926c3f319eda178d1bd90851e4317e6d8cdb5e292a3386aac9bd75eca29cf9c7"
+                "sha256:2656e1a6edcdabf4275f9a3640db59fd5de107d88e8663c5d4e9a0fa62f77f94",
+                "sha256:534ef71d539ae97d4c3a4cf7d6f110f214b0e687e92f9cb9d2a3b0d3101289c8"
             ],
-            "version": "==2.7.1"
+            "version": "==2.8.1"
         },
         "pyinotify": {
             "hashes": [
@@ -165,53 +193,91 @@
         },
         "pymdown-extensions": {
             "hashes": [
-                "sha256:9ba704052d4bdc04a7cd63f7db4ef6add73bafcef22c0cf6b2e3386cf4ece51e",
-                "sha256:a3689c04f4cbddacd9d569425c571ae07e2673cc4df63a26cdbf1abc15229137"
+                "sha256:478b2c04513fbb2db61688d5f6e9030a92fb9be14f1f383535c43f7be9dff95b",
+                "sha256:632371fa3bf1b21a0e3f4063010da59b41db049f261f4c0b0872069a9b6d1735"
             ],
             "index": "pypi",
-            "version": "==8.0.1"
+            "version": "==8.1.1"
         },
         "pyyaml": {
             "hashes": [
-                "sha256:06a0d7ba600ce0b2d2fe2e78453a470b5a6e000a985dd4a4e54e436cc36b0e97",
-                "sha256:240097ff019d7c70a4922b6869d8a86407758333f02203e0fc6ff79c5dcede76",
-                "sha256:4f4b913ca1a7319b33cfb1369e91e50354d6f07a135f3b901aca02aa95940bd2",
-                "sha256:69f00dca373f240f842b2931fb2c7e14ddbacd1397d57157a9b005a6a9942648",
-                "sha256:73f099454b799e05e5ab51423c7bcf361c58d3206fa7b0d555426b1f4d9a3eaf",
-                "sha256:74809a57b329d6cc0fdccee6318f44b9b8649961fa73144a98735b0aaf029f1f",
-                "sha256:7739fc0fa8205b3ee8808aea45e968bc90082c10aef6ea95e855e10abf4a37b2",
-                "sha256:95f71d2af0ff4227885f7a6605c37fd53d3a106fcab511b8860ecca9fcf400ee",
-                "sha256:b8eac752c5e14d3eca0e6dd9199cd627518cb5ec06add0de9d32baeee6fe645d",
-                "sha256:cc8955cfbfc7a115fa81d85284ee61147059a753344bc51098f3ccd69b0d7e0c",
-                "sha256:d13155f591e6fcc1ec3b30685d50bf0711574e2c0dfffd7644babf8b5102ca1a"
+                "sha256:08682f6b72c722394747bddaf0aa62277e02557c0fd1c42cb853016a38f8dedf",
+                "sha256:0f5f5786c0e09baddcd8b4b45f20a7b5d61a7e7e99846e3c799b05c7c53fa696",
+                "sha256:129def1b7c1bf22faffd67b8f3724645203b79d8f4cc81f674654d9902cb4393",
+                "sha256:294db365efa064d00b8d1ef65d8ea2c3426ac366c0c4368d930bf1c5fb497f77",
+                "sha256:3b2b1824fe7112845700f815ff6a489360226a5609b96ec2190a45e62a9fc922",
+                "sha256:3bd0e463264cf257d1ffd2e40223b197271046d09dadf73a0fe82b9c1fc385a5",
+                "sha256:4465124ef1b18d9ace298060f4eccc64b0850899ac4ac53294547536533800c8",
+                "sha256:49d4cdd9065b9b6e206d0595fee27a96b5dd22618e7520c33204a4a3239d5b10",
+                "sha256:4e0583d24c881e14342eaf4ec5fbc97f934b999a6828693a99157fde912540cc",
+                "sha256:5accb17103e43963b80e6f837831f38d314a0495500067cb25afab2e8d7a4018",
+                "sha256:607774cbba28732bfa802b54baa7484215f530991055bb562efbed5b2f20a45e",
+                "sha256:6c78645d400265a062508ae399b60b8c167bf003db364ecb26dcab2bda048253",
+                "sha256:72a01f726a9c7851ca9bfad6fd09ca4e090a023c00945ea05ba1638c09dc3347",
+                "sha256:74c1485f7707cf707a7aef42ef6322b8f97921bd89be2ab6317fd782c2d53183",
+                "sha256:895f61ef02e8fed38159bb70f7e100e00f471eae2bc838cd0f4ebb21e28f8541",
+                "sha256:8c1be557ee92a20f184922c7b6424e8ab6691788e6d86137c5d93c1a6ec1b8fb",
+                "sha256:bb4191dfc9306777bc594117aee052446b3fa88737cd13b7188d0e7aa8162185",
+                "sha256:bfb51918d4ff3d77c1c856a9699f8492c612cde32fd3bcd344af9be34999bfdc",
+                "sha256:c20cfa2d49991c8b4147af39859b167664f2ad4561704ee74c1de03318e898db",
+                "sha256:cb333c16912324fd5f769fff6bc5de372e9e7a202247b48870bc251ed40239aa",
+                "sha256:d2d9808ea7b4af864f35ea216be506ecec180628aced0704e34aca0b040ffe46",
+                "sha256:d483ad4e639292c90170eb6f7783ad19490e7a8defb3e46f97dfe4bacae89122",
+                "sha256:dd5de0646207f053eb0d6c74ae45ba98c3395a571a2891858e87df7c9b9bd51b",
+                "sha256:e1d4970ea66be07ae37a3c2e48b5ec63f7ba6804bdddfdbd3cfd954d25a82e63",
+                "sha256:e4fac90784481d221a8e4b1162afa7c47ed953be40d31ab4629ae917510051df",
+                "sha256:fa5ae20527d8e831e8230cbffd9f8fe952815b2b7dae6ffec25318803a7528fc",
+                "sha256:fd7f6999a8070df521b6384004ef42833b9bd62cfee11a09bda1079b4b704247",
+                "sha256:fdc842473cd33f45ff6bce46aea678a54e3d21f1b61a7750ce3c498eedfe25d6",
+                "sha256:fe69978f3f768926cfa37b867e3843918e012cf83f680806599ddce33c2c68b0"
             ],
-            "version": "==5.3.1"
+            "version": "==5.4.1"
         },
         "regex": {
             "hashes": [
-                "sha256:088afc8c63e7bd187a3c70a94b9e50ab3f17e1d3f52a32750b5b77dbe99ef5ef",
-                "sha256:1fe0a41437bbd06063aa184c34804efa886bcc128222e9916310c92cd54c3b4c",
-                "sha256:41bb65f54bba392643557e617316d0d899ed5b4946dccee1cb6696152b29844b",
-                "sha256:4318d56bccfe7d43e5addb272406ade7a2274da4b70eb15922a071c58ab0108c",
-                "sha256:4707f3695b34335afdfb09be3802c87fa0bc27030471dbc082f815f23688bc63",
-                "sha256:5533a959a1748a5c042a6da71fe9267a908e21eded7a4f373efd23a2cbdb0ecc",
-                "sha256:5f18875ac23d9aa2f060838e8b79093e8bb2313dbaaa9f54c6d8e52a5df097be",
-                "sha256:60b0e9e6dc45683e569ec37c55ac20c582973841927a85f2d8a7d20ee80216ab",
-                "sha256:84e9407db1b2eb368b7ecc283121b5e592c9aaedbe8c78b1a2f1102eb2e21d19",
-                "sha256:8d69cef61fa50c8133382e61fd97439de1ae623fe943578e477e76a9d9471637",
-                "sha256:9a02d0ae31d35e1ec12a4ea4d4cca990800f66a917d0fb997b20fbc13f5321fc",
-                "sha256:9bc13e0d20b97ffb07821aa3e113f9998e84994fe4d159ffa3d3a9d1b805043b",
-                "sha256:a6f32aea4260dfe0e55dc9733ea162ea38f0ea86aa7d0f77b15beac5bf7b369d",
-                "sha256:ae91972f8ac958039920ef6e8769277c084971a142ce2b660691793ae44aae6b",
-                "sha256:c570f6fa14b9c4c8a4924aaad354652366577b4f98213cf76305067144f7b100",
-                "sha256:d23a18037313714fb3bb5a94434d3151ee4300bae631894b1ac08111abeaa4a3",
-                "sha256:eaf548d117b6737df379fdd53bdde4f08870e66d7ea653e230477f071f861121",
-                "sha256:ebbe29186a3d9b0c591e71b7393f1ae08c83cb2d8e517d2a822b8f7ec99dfd8b",
-                "sha256:eda4771e0ace7f67f58bc5b560e27fb20f32a148cbc993b0c3835970935c2707",
-                "sha256:f1b3afc574a3db3b25c89161059d857bd4909a1269b0b3cb3c904677c8c4a3f7",
-                "sha256:f2388013e68e750eaa16ccbea62d4130180c26abb1d8e5d584b9baf69672b30f"
+                "sha256:01afaf2ec48e196ba91b37451aa353cb7eda77efe518e481707e0515025f0cd5",
+                "sha256:11d773d75fa650cd36f68d7ca936e3c7afaae41b863b8c387a22aaa78d3c5c79",
+                "sha256:18c071c3eb09c30a264879f0d310d37fe5d3a3111662438889ae2eb6fc570c31",
+                "sha256:1e1c20e29358165242928c2de1482fb2cf4ea54a6a6dea2bd7a0e0d8ee321500",
+                "sha256:281d2fd05555079448537fe108d79eb031b403dac622621c78944c235f3fcf11",
+                "sha256:314d66636c494ed9c148a42731b3834496cc9a2c4251b1661e40936814542b14",
+                "sha256:32e65442138b7b76dd8173ffa2cf67356b7bc1768851dded39a7a13bf9223da3",
+                "sha256:339456e7d8c06dd36a22e451d58ef72cef293112b559010db3d054d5560ef439",
+                "sha256:3916d08be28a1149fb97f7728fca1f7c15d309a9f9682d89d79db75d5e52091c",
+                "sha256:3a9cd17e6e5c7eb328517969e0cb0c3d31fd329298dd0c04af99ebf42e904f82",
+                "sha256:47bf5bf60cf04d72bf6055ae5927a0bd9016096bf3d742fa50d9bf9f45aa0711",
+                "sha256:4c46e22a0933dd783467cf32b3516299fb98cfebd895817d685130cc50cd1093",
+                "sha256:4c557a7b470908b1712fe27fb1ef20772b78079808c87d20a90d051660b1d69a",
+                "sha256:52ba3d3f9b942c49d7e4bc105bb28551c44065f139a65062ab7912bef10c9afb",
+                "sha256:563085e55b0d4fb8f746f6a335893bda5c2cef43b2f0258fe1020ab1dd874df8",
+                "sha256:598585c9f0af8374c28edd609eb291b5726d7cbce16be6a8b95aa074d252ee17",
+                "sha256:619d71c59a78b84d7f18891fe914446d07edd48dc8328c8e149cbe0929b4e000",
+                "sha256:67bdb9702427ceddc6ef3dc382455e90f785af4c13d495f9626861763ee13f9d",
+                "sha256:6d1b01031dedf2503631d0903cb563743f397ccaf6607a5e3b19a3d76fc10480",
+                "sha256:741a9647fcf2e45f3a1cf0e24f5e17febf3efe8d4ba1281dcc3aa0459ef424dc",
+                "sha256:7c2a1af393fcc09e898beba5dd59196edaa3116191cc7257f9224beaed3e1aa0",
+                "sha256:7d9884d86dd4dd489e981d94a65cd30d6f07203d90e98f6f657f05170f6324c9",
+                "sha256:90f11ff637fe8798933fb29f5ae1148c978cccb0452005bf4c69e13db951e765",
+                "sha256:919859aa909429fb5aa9cf8807f6045592c85ef56fdd30a9a3747e513db2536e",
+                "sha256:96fcd1888ab4d03adfc9303a7b3c0bd78c5412b2bfbe76db5b56d9eae004907a",
+                "sha256:97f29f57d5b84e73fbaf99ab3e26134e6687348e95ef6b48cfd2c06807005a07",
+                "sha256:980d7be47c84979d9136328d882f67ec5e50008681d94ecc8afa8a65ed1f4a6f",
+                "sha256:a91aa8619b23b79bcbeb37abe286f2f408d2f2d6f29a17237afda55bb54e7aac",
+                "sha256:ade17eb5d643b7fead300a1641e9f45401c98eee23763e9ed66a43f92f20b4a7",
+                "sha256:b9c3db21af35e3b3c05764461b262d6f05bbca08a71a7849fd79d47ba7bc33ed",
+                "sha256:bd28bc2e3a772acbb07787c6308e00d9626ff89e3bfcdebe87fa5afbfdedf968",
+                "sha256:bf5824bfac591ddb2c1f0a5f4ab72da28994548c708d2191e3b87dd207eb3ad7",
+                "sha256:c0502c0fadef0d23b128605d69b58edb2c681c25d44574fc673b0e52dce71ee2",
+                "sha256:c38c71df845e2aabb7fb0b920d11a1b5ac8526005e533a8920aea97efb8ec6a4",
+                "sha256:ce15b6d103daff8e9fee13cf7f0add05245a05d866e73926c358e871221eae87",
+                "sha256:d3029c340cfbb3ac0a71798100ccc13b97dddf373a4ae56b6a72cf70dfd53bc8",
+                "sha256:e512d8ef5ad7b898cdb2d8ee1cb09a8339e4f8be706d27eaa180c2f177248a10",
+                "sha256:e8e5b509d5c2ff12f8418006d5a90e9436766133b564db0abaec92fd27fcee29",
+                "sha256:ee54ff27bf0afaf4c3b3a62bcd016c12c3fdb4ec4f413391a90bd38bc3624605",
+                "sha256:fa4537fb4a98fe8fde99626e4681cc644bdcf2a795038533f9f711513a862ae6",
+                "sha256:fd45ff9293d9274c5008a2054ecef86a9bfe819a67c7be1afb65e69b405b3042"
             ],
-            "version": "==2020.9.27"
+            "version": "==2021.4.4"
         },
         "six": {
             "hashes": [
@@ -222,24 +288,56 @@
         },
         "tornado": {
             "hashes": [
-                "sha256:0fe2d45ba43b00a41cd73f8be321a44936dc1aba233dee979f17a042b83eb6dc",
-                "sha256:22aed82c2ea340c3771e3babc5ef220272f6fd06b5108a53b4976d0d722bcd52",
-                "sha256:2c027eb2a393d964b22b5c154d1a23a5f8727db6fda837118a776b29e2b8ebc6",
-                "sha256:5217e601700f24e966ddab689f90b7ea4bd91ff3357c3600fa1045e26d68e55d",
-                "sha256:5618f72e947533832cbc3dec54e1dffc1747a5cb17d1fd91577ed14fa0dc081b",
-                "sha256:5f6a07e62e799be5d2330e68d808c8ac41d4a259b9cea61da4101b83cb5dc673",
-                "sha256:c58d56003daf1b616336781b26d184023ea4af13ae143d9dda65e31e534940b9",
-                "sha256:c952975c8ba74f546ae6de2e226ab3cc3cc11ae47baf607459a6728585bb542a",
-                "sha256:c98232a3ac391f5faea6821b53db8db461157baa788f5d6222a193e9456e1740"
+                "sha256:0a00ff4561e2929a2c37ce706cb8233b7907e0cdc22eab98888aca5dd3775feb",
+                "sha256:0d321a39c36e5f2c4ff12b4ed58d41390460f798422c4504e09eb5678e09998c",
+                "sha256:1e8225a1070cd8eec59a996c43229fe8f95689cb16e552d130b9793cb570a288",
+                "sha256:20241b3cb4f425e971cb0a8e4ffc9b0a861530ae3c52f2b0434e6c1b57e9fd95",
+                "sha256:25ad220258349a12ae87ede08a7b04aca51237721f63b1808d39bdb4b2164558",
+                "sha256:33892118b165401f291070100d6d09359ca74addda679b60390b09f8ef325ffe",
+                "sha256:33c6e81d7bd55b468d2e793517c909b139960b6c790a60b7991b9b6b76fb9791",
+                "sha256:3447475585bae2e77ecb832fc0300c3695516a47d46cefa0528181a34c5b9d3d",
+                "sha256:34ca2dac9e4d7afb0bed4677512e36a52f09caa6fded70b4e3e1c89dbd92c326",
+                "sha256:3e63498f680547ed24d2c71e6497f24bca791aca2fe116dbc2bd0ac7f191691b",
+                "sha256:548430be2740e327b3fe0201abe471f314741efcb0067ec4f2d7dcfb4825f3e4",
+                "sha256:6196a5c39286cc37c024cd78834fb9345e464525d8991c21e908cc046d1cc02c",
+                "sha256:61b32d06ae8a036a6607805e6720ef00a3c98207038444ba7fd3d169cd998910",
+                "sha256:6286efab1ed6e74b7028327365cf7346b1d777d63ab30e21a0f4d5b275fc17d5",
+                "sha256:65d98939f1a2e74b58839f8c4dab3b6b3c1ce84972ae712be02845e65391ac7c",
+                "sha256:66324e4e1beede9ac79e60f88de548da58b1f8ab4b2f1354d8375774f997e6c0",
+                "sha256:6c77c9937962577a6a76917845d06af6ab9197702a42e1346d8ae2e76b5e3675",
+                "sha256:70dec29e8ac485dbf57481baee40781c63e381bebea080991893cd297742b8fd",
+                "sha256:7250a3fa399f08ec9cb3f7b1b987955d17e044f1ade821b32e5f435130250d7f",
+                "sha256:748290bf9112b581c525e6e6d3820621ff020ed95af6f17fedef416b27ed564c",
+                "sha256:7da13da6f985aab7f6f28debab00c67ff9cbacd588e8477034c0652ac141feea",
+                "sha256:8f959b26f2634a091bb42241c3ed8d3cedb506e7c27b8dd5c7b9f745318ddbb6",
+                "sha256:9de9e5188a782be6b1ce866e8a51bc76a0fbaa0e16613823fc38e4fc2556ad05",
+                "sha256:a48900ecea1cbb71b8c71c620dee15b62f85f7c14189bdeee54966fbd9a0c5bd",
+                "sha256:b87936fd2c317b6ee08a5741ea06b9d11a6074ef4cc42e031bc6403f82a32575",
+                "sha256:c77da1263aa361938476f04c4b6c8916001b90b2c2fdd92d8d535e1af48fba5a",
+                "sha256:cb5ec8eead331e3bb4ce8066cf06d2dfef1bfb1b2a73082dfe8a161301b76e37",
+                "sha256:cc0ee35043162abbf717b7df924597ade8e5395e7b66d18270116f8745ceb795",
+                "sha256:d14d30e7f46a0476efb0deb5b61343b1526f73ebb5ed84f23dc794bdb88f9d9f",
+                "sha256:d371e811d6b156d82aa5f9a4e08b58debf97c302a35714f6f45e35139c332e32",
+                "sha256:d3d20ea5782ba63ed13bc2b8c291a053c8d807a8fa927d941bd718468f7b950c",
+                "sha256:d3f7594930c423fd9f5d1a76bee85a2c36fd8b4b16921cae7e965f22575e9c01",
+                "sha256:dcef026f608f678c118779cd6591c8af6e9b4155c44e0d1bc0c87c036fb8c8c4",
+                "sha256:e0791ac58d91ac58f694d8d2957884df8e4e2f6687cdf367ef7eb7497f79eaa2",
+                "sha256:e385b637ac3acaae8022e7e47dfa7b83d3620e432e3ecb9a3f7f58f150e50921",
+                "sha256:e519d64089b0876c7b467274468709dadf11e41d65f63bba207e04217f47c085",
+                "sha256:e7229e60ac41a1202444497ddde70a48d33909e484f96eb0da9baf8dc68541df",
+                "sha256:ed3ad863b1b40cd1d4bd21e7498329ccaece75db5a5bf58cd3c9f130843e7102",
+                "sha256:f0ba29bafd8e7e22920567ce0d232c26d4d47c8b5cf4ed7b562b5db39fa199c5",
+                "sha256:fa2ba70284fa42c2a5ecb35e322e68823288a4251f9ba9cc77be04ae15eada68",
+                "sha256:fba85b6cd9c39be262fcd23865652920832b61583de2a2ca907dbd8e8a8c81e5"
             ],
-            "version": "==6.0.4"
+            "version": "==6.1"
         },
         "tqdm": {
             "hashes": [
-                "sha256:2dd75fdb764f673b8187643496fcfbeac38348015b665878e582b152f3391cdb",
-                "sha256:93b7a6a9129fce904f6df4cf3ae7ff431d779be681a95c3344c26f3e6c09abfa"
+                "sha256:daec693491c52e9498632dfbe9ccfc4882a557f5fa08982db1b4d3adbe0887c3",
+                "sha256:ebdebdb95e3477ceea267decfc0784859aa3df3e27e22d23b83e9b272bf157ae"
             ],
-            "version": "==4.50.0"
+            "version": "==4.60.0"
         }
     },
     "develop": {}
diff --git a/docs/.empty b/docs/.empty
deleted file mode 100644
index e69de29..0000000
diff --git a/QUESTIONS.md b/docs/_questions.md
similarity index 100%
rename from QUESTIONS.md
rename to docs/_questions.md
diff --git a/REFERENCES.md b/docs/_references.md
similarity index 100%
rename from REFERENCES.md
rename to docs/_references.md
diff --git a/docs/images b/docs/images
new file mode 120000
index 0000000..5e67573
--- /dev/null
+++ b/docs/images
@@ -0,0 +1 @@
+../images
\ No newline at end of file
diff --git a/mkdocs.yml b/mkdocs.yml
index 79297aa..8148f49 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -61,6 +61,8 @@ markdown_extensions:
   # pip install pymdown-extensions
   - pymdownx.superfences:
 
+plugins: []
+
 extra:
   search:
     language: 'fr, en'
diff --git a/package-lock.json b/package-lock.json
index bb6f42a..489213a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -509,9 +509,9 @@
       }
     },
     "caniuse-lite": {
-      "version": "1.0.30001038",
-      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001038.tgz",
-      "integrity": "sha512-zii9quPo96XfOiRD4TrfYGs+QsGZpb2cGiMAzPjtf/hpFgB6zCPZgJb7I1+EATeMw/o+lG8FyRAnI+CWStHcaQ=="
+      "version": "1.0.30001208",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001208.tgz",
+      "integrity": "sha512-OE5UE4+nBOro8Dyvv0lfx+SRtfVIOM9uhKqFmJeUbGriqhhStgp1A0OyBpgy3OUF8AhYCT+PVwPC1gMl2ZcQMA=="
     },
     "carlo": {
       "version": "0.9.46",
diff --git a/slides/images b/slides/images
new file mode 120000
index 0000000..5e67573
--- /dev/null
+++ b/slides/images
@@ -0,0 +1 @@
+../images
\ No newline at end of file