diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 45538b4..2a09e37 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -1,5 +1,7 @@
 # sync with https://github.com/fphammerle/ical2vdir/blob/master/.github/workflows/python.yml
 
+# https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions
+
 # shown in badge
 # https://help.github.com/en/actions/automating-your-workflow-with-github-actions/configuring-a-workflow#adding-a-workflow-status-badge-to-your-repository
 name: tests
@@ -11,7 +13,24 @@ on:
   - cron: '0 20 * * 5'
 
 jobs:
-  build:
+  code-format:
+    runs-on: ubuntu-18.04
+    strategy:
+      matrix:
+        python-version:
+        - 3.8
+    steps:
+    - uses: actions/checkout@v1
+    - uses: actions/setup-python@v1
+      with:
+        python-version: ${{ matrix.python-version }}
+    - run: pip install --upgrade pipenv>=2018.10.9
+    - run: pipenv install --python "$PYTHON_VERSION" --deploy --dev
+      env:
+        PYTHON_VERSION: ${{ matrix.python-version }}
+    - run: pipenv graph
+    - run: pipenv run black --check .
+  tests:
     runs-on: ubuntu-18.04
     strategy:
       matrix:
@@ -26,7 +45,9 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
     - run: pip install --upgrade pipenv>=2018.10.9
-    - run: pipenv install --deploy --dev
+    - run: pipenv install --python "$PYTHON_VERSION" --deploy --dev
+      env:
+        PYTHON_VERSION: ${{ matrix.python-version }}
     # ModuleNotFoundError: No module named 'importlib_metadata'
     # https://github.com/WanzenBug/pylint-import-requirements/issues/17
     - run: if python3 -c 'import sys; sys.exit(sys.version_info < (3, 8))'; then
@@ -34,12 +55,11 @@ jobs:
            pipenv install --dev importlib-metadata;
            fi
     - run: pipenv graph
+    - run: pipenv run pytest --cov=switchbot_mqtt --cov-report=term-missing --cov-fail-under=100
     - run: pipenv run pylint --load-plugins=pylint_import_requirements switchbot_mqtt
     # https://github.com/PyCQA/pylint/issues/352
     - run: pipenv run pylint tests/*
     - run: pipenv run mypy switchbot_mqtt tests
-    - run: pipenv run pytest --cov=switchbot_mqtt --cov-report=term-missing --cov-fail-under=100
-    - run: pipenv run black --check .
     # >=1.9.0 to detect branch name
     # https://github.com/coveralls-clients/coveralls-python/pull/207
     # https://github.com/coverallsapp/github-action/issues/4#issuecomment-547036866
diff --git a/.gitignore b/.gitignore
index 35dd640..34fd590 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 .mypy_cache/
 build/
 dist/
+tags/
diff --git a/Pipfile b/Pipfile
index 6d53b41..16a92cd 100644
--- a/Pipfile
+++ b/Pipfile
@@ -7,12 +7,24 @@ name = "pypi"
 switchbot-mqtt = {editable = true,path = "."}
 
 [dev-packages]
-black = "==19.10b0"
+# black requires python>=3.6
+# https://github.com/psf/black/commit/e74117f172e29e8a980e2c9de929ad50d3769150#diff-2eeaed663bd0d25b7e608891384b7298R51
+black = {version = "==19.10b0", markers = "python_version >= '3.6'"}
 mypy = "*"
 pylint = "*"
 pylint-import-requirements = "*"
 pytest = "*"
 pytest-cov = "*"
 
+# python3.5 compatibility
+# https://github.com/jaraco/zipp/commit/05a3c52b4d41690e0471a2e283cffb500dc0329a
+zipp = "<2"
+# workaround https://github.com/pytest-dev/pytest/issues/3953
+pathlib2 = {version = "*", markers="python_version < '3.6'"}
+
+# python3.8 compatibility
+# workaround https://github.com/WanzenBug/pylint-import-requirements/issues/17
+importlib-metadata = "*"
+
 [requires]
 python_version = "3"
diff --git a/Pipfile.lock b/Pipfile.lock
index 6975af6..cd41c86 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "5495f7efdf5fb0e6faa95b22a5ccd09f8ab59b9d7277c738c8c698f6a66da61e"
+            "sha256": "434215627faf07abdfe5fa8f157dd6a417ebbddc87b6200c15fd38e1643c198b"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -42,17 +42,17 @@
     "develop": {
         "appdirs": {
             "hashes": [
-                "sha256:9e5896d1372858f8dd3344faf4e5014d21849c756c8d5701f78f8a103b372d92",
-                "sha256:d8b24664561d0d34ddfaec54636d502d7cea6e29c3eaf68f3df6180863e2166e"
+                "sha256:7d5d0167b2b1ba821647616af46a749d1c653740dd0d2415100fe26e27afdf41",
+                "sha256:a841dacd6b99318a741b166adb07e19ee71a274450e68237b4650ca1055ab128"
             ],
-            "version": "==1.4.3"
+            "version": "==1.4.4"
         },
         "astroid": {
             "hashes": [
-                "sha256:4c17cea3e592c21b6e222f673868961bad77e1f985cb1694ed077475a89229c1",
-                "sha256:d8506842a3faf734b81599c8b98dcc423de863adcc1999248480b18bd31a0f38"
+                "sha256:2f4078c2a41bf377eea06d71c9d2ba4eb8f6b1af2135bec27bbbb7d8f12bb703",
+                "sha256:bc58d83eb610252fd8de6363e39d4f1d0619c894b0ed24603b881c02e64c7386"
             ],
-            "version": "==2.4.1"
+            "version": "==2.4.2"
         },
         "attrs": {
             "hashes": [
@@ -67,6 +67,7 @@
                 "sha256:c2edb73a08e9e0e6f65a0e6af18b059b8b1cdd5bef997d7a0b181df93dc81539"
             ],
             "index": "pypi",
+            "markers": "python_version >= '3.6'",
             "version": "==19.10b0"
         },
         "click": {
@@ -114,11 +115,11 @@
         },
         "importlib-metadata": {
             "hashes": [
-                "sha256:2a688cbaa90e0cc587f1df48bdc97a6eadccdcd9c35fb3f976a09e3b5016d90f",
-                "sha256:34513a8a0c4962bc66d35b359558fd8a5e10cd472d37aec5f66858addef32c1e"
+                "sha256:0505dd08068cfec00f53a74a0ad927676d7757da81b7436a6eefe4c7cf75c545",
+                "sha256:15ec6c0fd909e893e3a08b3a7c76ecb149122fb14b7efe1199ddd4c7c57ea958"
             ],
-            "markers": "python_version < '3.8'",
-            "version": "==1.6.0"
+            "index": "pypi",
+            "version": "==1.6.1"
         },
         "isort": {
             "hashes": [
@@ -162,30 +163,30 @@
         },
         "more-itertools": {
             "hashes": [
-                "sha256:5dd8bcf33e5f9513ffa06d5ad33d78f31e1931ac9a18f33d37e77a180d393a7c",
-                "sha256:b1ddb932186d8a6ac451e1d95844b382f55e12686d51ca0c68b6f61f2ab7a507"
+                "sha256:68c70cc7167bdf5c7c9d8f6954a7837089c6a36bf565383919bb595efb8a17e5",
+                "sha256:b78134b2063dd214000685165d81c154522c3ee0a1c0d4d113c80361c234c5a2"
             ],
-            "version": "==8.2.0"
+            "version": "==8.4.0"
         },
         "mypy": {
             "hashes": [
-                "sha256:15b948e1302682e3682f11f50208b726a246ab4e6c1b39f9264a8796bb416aa2",
-                "sha256:219a3116ecd015f8dca7b5d2c366c973509dfb9a8fc97ef044a36e3da66144a1",
-                "sha256:3b1fc683fb204c6b4403a1ef23f0b1fac8e4477091585e0c8c54cbdf7d7bb164",
-                "sha256:3beff56b453b6ef94ecb2996bea101a08f1f8a9771d3cbf4988a61e4d9973761",
-                "sha256:7687f6455ec3ed7649d1ae574136835a4272b65b3ddcf01ab8704ac65616c5ce",
-                "sha256:7ec45a70d40ede1ec7ad7f95b3c94c9cf4c186a32f6bacb1795b60abd2f9ef27",
-                "sha256:86c857510a9b7c3104cf4cde1568f4921762c8f9842e987bc03ed4f160925754",
-                "sha256:8a627507ef9b307b46a1fea9513d5c98680ba09591253082b4c48697ba05a4ae",
-                "sha256:8dfb69fbf9f3aeed18afffb15e319ca7f8da9642336348ddd6cab2713ddcf8f9",
-                "sha256:a34b577cdf6313bf24755f7a0e3f3c326d5c1f4fe7422d1d06498eb25ad0c600",
-                "sha256:a8ffcd53cb5dfc131850851cc09f1c44689c2812d0beb954d8138d4f5fc17f65",
-                "sha256:b90928f2d9eb2f33162405f32dde9f6dcead63a0971ca8a1b50eb4ca3e35ceb8",
-                "sha256:c56ffe22faa2e51054c5f7a3bc70a370939c2ed4de308c690e7949230c995913",
-                "sha256:f91c7ae919bbc3f96cd5e5b2e786b2b108343d1d7972ea130f7de27fdd547cf3"
+                "sha256:00cb1964a7476e871d6108341ac9c1a857d6bd20bf5877f4773ac5e9d92cd3cd",
+                "sha256:127de5a9b817a03a98c5ae8a0c46a20dc44442af6dcfa2ae7f96cb519b312efa",
+                "sha256:1f3976a945ad7f0a0727aafdc5651c2d3278e3c88dee94e2bf75cd3386b7b2f4",
+                "sha256:2f8c098f12b402c19b735aec724cc9105cc1a9eea405d08814eb4b14a6fb1a41",
+                "sha256:4ef13b619a289aa025f2273e05e755f8049bb4eaba6d703a425de37d495d178d",
+                "sha256:5d142f219bf8c7894dfa79ebfb7d352c4c63a325e75f10dfb4c3db9417dcd135",
+                "sha256:62eb5dd4ea86bda8ce386f26684f7f26e4bfe6283c9f2b6ca6d17faf704dcfad",
+                "sha256:64c36eb0936d0bfb7d8da49f92c18e312ad2e3ed46e5548ae4ca997b0d33bd59",
+                "sha256:75eed74d2faf2759f79c5f56f17388defd2fc994222312ec54ee921e37b31ad4",
+                "sha256:974bebe3699b9b46278a7f076635d219183da26e1a675c1f8243a69221758273",
+                "sha256:a5e5bb12b7982b179af513dddb06fca12285f0316d74f3964078acbfcf4c68f2",
+                "sha256:d31291df31bafb997952dc0a17ebb2737f802c754aed31dd155a8bfe75112c57",
+                "sha256:d3b4941de44341227ece1caaf5b08b23e42ad4eeb8b603219afb11e9d4cfb437",
+                "sha256:eadb865126da4e3c4c95bdb47fe1bb087a3e3ea14d39a3b13224b8a4d9f9a102"
             ],
             "index": "pypi",
-            "version": "==0.770"
+            "version": "==0.780"
         },
         "mypy-extensions": {
             "hashes": [
@@ -196,10 +197,19 @@
         },
         "packaging": {
             "hashes": [
-                "sha256:3c292b474fda1671ec57d46d739d072bfd495a4f51ad01a055121d81e952b7a3",
-                "sha256:82f77b9bee21c1bafbf35a84905d604d5d1223801d639cf3ed140bd651c08752"
+                "sha256:4357f74f47b9c12db93624a82154e9b120fa8293699949152b22065d556079f8",
+                "sha256:998416ba6962ae7fbd6596850b80e17859a5753ba17c32284f67bfff33784181"
             ],
-            "version": "==20.3"
+            "version": "==20.4"
+        },
+        "pathlib2": {
+            "hashes": [
+                "sha256:0ec8205a157c80d7acc301c0b18fbd5d44fe655968f5d947b6ecef5290fc35db",
+                "sha256:6cd9a47b597b37cc57de1c05e56fb1a1c9cc9fab04fe78c29acd090418529868"
+            ],
+            "index": "pypi",
+            "markers": "python_version < '3.6'",
+            "version": "==2.3.5"
         },
         "pathspec": {
             "hashes": [
@@ -217,18 +227,18 @@
         },
         "py": {
             "hashes": [
-                "sha256:5e27081401262157467ad6e7f851b7aa402c5852dbcb3dae06768434de5752aa",
-                "sha256:c20fdd83a5dbc0af9efd622bee9a5564e278f6380fffcacc43ba6f43db2813b0"
+                "sha256:a673fa23d7000440cc885c17dbd34fafcb7d7a6e230b29f6766400de36a33c44",
+                "sha256:f3b3a4c36512a4c4f024041ab51866f11761cc169670204b235f6b20523d4e6b"
             ],
-            "version": "==1.8.1"
+            "version": "==1.8.2"
         },
         "pylint": {
             "hashes": [
-                "sha256:b95e31850f3af163c2283ed40432f053acbc8fc6eba6a069cb518d9dbf71848c",
-                "sha256:dd506acce0427e9e08fb87274bcaa953d38b50a58207170dbf5b36cf3e16957b"
+                "sha256:7dd78437f2d8d019717dbf287772d0b2dbdfd13fc016aa7faa08d67bccc46adc",
+                "sha256:d0ece7d223fe422088b0e8f13fa0a1e8eb745ebffcb8ed53d3e95394b6101a1c"
             ],
             "index": "pypi",
-            "version": "==2.5.2"
+            "version": "==2.5.3"
         },
         "pylint-import-requirements": {
             "hashes": [
@@ -247,59 +257,59 @@
         },
         "pytest": {
             "hashes": [
-                "sha256:0e5b30f5cb04e887b91b1ee519fa3d89049595f428c1db76e73bd7f17b09b172",
-                "sha256:84dde37075b8805f3d1f392cc47e38a0e59518fb46a431cfdaf7cf1ce805f970"
+                "sha256:5c0db86b698e8f170ba4582a492248919255fcd4c79b1ee64ace34301fb589a1",
+                "sha256:7979331bfcba207414f5e1263b5a0f8f521d0f457318836a7355531ed1a4c7d8"
             ],
             "index": "pypi",
-            "version": "==5.4.1"
+            "version": "==5.4.3"
         },
         "pytest-cov": {
             "hashes": [
-                "sha256:cc6742d8bac45070217169f5f72ceee1e0e55b0221f54bcf24845972d3a47f2b",
-                "sha256:cdbdef4f870408ebdbfeb44e63e07eb18bb4619fae852f6e760645fa36172626"
+                "sha256:1a629dc9f48e53512fcbfda6b07de490c374b0c83c55ff7a1720b3fccff0ac87",
+                "sha256:6e6d18092dce6fad667cd7020deed816f858ad3b49d5b5e2b1cc1c97a4dba65c"
             ],
             "index": "pypi",
-            "version": "==2.8.1"
+            "version": "==2.10.0"
         },
         "regex": {
             "hashes": [
-                "sha256:021a0ae4d2baeeb60a3014805a2096cb329bd6d9f30669b7ad0da51a9cb73349",
-                "sha256:04d6e948ef34d3eac133bedc0098364a9e635a7914f050edb61272d2ddae3608",
-                "sha256:099568b372bda492be09c4f291b398475587d49937c659824f891182df728cdf",
-                "sha256:0ff50843535593ee93acab662663cb2f52af8e31c3f525f630f1dc6156247938",
-                "sha256:1b17bf37c2aefc4cac8436971fe6ee52542ae4225cfc7762017f7e97a63ca998",
-                "sha256:1e2255ae938a36e9bd7db3b93618796d90c07e5f64dd6a6750c55f51f8b76918",
-                "sha256:2bc6a17a7fa8afd33c02d51b6f417fc271538990297167f68a98cae1c9e5c945",
-                "sha256:3ab5e41c4ed7cd4fa426c50add2892eb0f04ae4e73162155cd668257d02259dd",
-                "sha256:3b059e2476b327b9794c792c855aa05531a3f3044737e455d283c7539bd7534d",
-                "sha256:4df91094ced6f53e71f695c909d9bad1cca8761d96fd9f23db12245b5521136e",
-                "sha256:5493a02c1882d2acaaf17be81a3b65408ff541c922bfd002535c5f148aa29f74",
-                "sha256:5b741ecc3ad3e463d2ba32dce512b412c319993c1bb3d999be49e6092a769fb2",
-                "sha256:652ab4836cd5531d64a34403c00ada4077bb91112e8bcdae933e2eae232cf4a8",
-                "sha256:669a8d46764a09f198f2e91fc0d5acdac8e6b620376757a04682846ae28879c4",
-                "sha256:73a10404867b835f1b8a64253e4621908f0d71150eb4e97ab2e7e441b53e9451",
-                "sha256:7ce4a213a96d6c25eeae2f7d60d4dad89ac2b8134ec3e69db9bc522e2c0f9388",
-                "sha256:8127ca2bf9539d6a64d03686fd9e789e8c194fc19af49b69b081f8c7e6ecb1bc",
-                "sha256:b5b5b2e95f761a88d4c93691716ce01dc55f288a153face1654f868a8034f494",
-                "sha256:b7c9f65524ff06bf70c945cd8d8d1fd90853e27ccf86026af2afb4d9a63d06b1",
-                "sha256:f7f2f4226db6acd1da228adf433c5c3792858474e49d80668ea82ac87cf74a03",
-                "sha256:fa09da4af4e5b15c0e8b4986a083f3fd159302ea115a6cc0649cd163435538b8"
-            ],
-            "version": "==2020.5.7"
+                "sha256:08997a37b221a3e27d68ffb601e45abfb0093d39ee770e4257bd2f5115e8cb0a",
+                "sha256:112e34adf95e45158c597feea65d06a8124898bdeac975c9087fe71b572bd938",
+                "sha256:1700419d8a18c26ff396b3b06ace315b5f2a6e780dad387e4c48717a12a22c29",
+                "sha256:2f6f211633ee8d3f7706953e9d3edc7ce63a1d6aad0be5dcee1ece127eea13ae",
+                "sha256:52e1b4bef02f4040b2fd547357a170fc1146e60ab310cdbdd098db86e929b387",
+                "sha256:55b4c25cbb3b29f8d5e63aeed27b49fa0f8476b0d4e1b3171d85db891938cc3a",
+                "sha256:5aaa5928b039ae440d775acea11d01e42ff26e1561c0ffcd3d805750973c6baf",
+                "sha256:654cb773b2792e50151f0e22be0f2b6e1c3a04c5328ff1d9d59c0398d37ef610",
+                "sha256:690f858d9a94d903cf5cada62ce069b5d93b313d7d05456dbcd99420856562d9",
+                "sha256:6ad8663c17db4c5ef438141f99e291c4d4edfeaacc0ce28b5bba2b0bf273d9b5",
+                "sha256:89cda1a5d3e33ec9e231ece7307afc101b5217523d55ef4dc7fb2abd6de71ba3",
+                "sha256:92d8a043a4241a710c1cf7593f5577fbb832cf6c3a00ff3fc1ff2052aff5dd89",
+                "sha256:95fa7726d073c87141f7bbfb04c284901f8328e2d430eeb71b8ffdd5742a5ded",
+                "sha256:97712e0d0af05febd8ab63d2ef0ab2d0cd9deddf4476f7aa153f76feef4b2754",
+                "sha256:b2ba0f78b3ef375114856cbdaa30559914d081c416b431f2437f83ce4f8b7f2f",
+                "sha256:bae83f2a56ab30d5353b47f9b2a33e4aac4de9401fb582b55c42b132a8ac3868",
+                "sha256:c78e66a922de1c95a208e4ec02e2e5cf0bb83a36ceececc10a72841e53fbf2bd",
+                "sha256:cf59bbf282b627130f5ba68b7fa3abdb96372b24b66bdf72a4920e8153fc7910",
+                "sha256:e3cdc9423808f7e1bb9c2e0bdb1c9dc37b0607b30d646ff6faf0d4e41ee8fee3",
+                "sha256:e9b64e609d37438f7d6e68c2546d2cb8062f3adb27e6336bc129b51be20773ac",
+                "sha256:fbff901c54c22425a5b809b914a3bfaf4b9570eee0e5ce8186ac71eb2025191c"
+            ],
+            "version": "==2020.6.8"
         },
         "six": {
             "hashes": [
-                "sha256:236bdbdce46e6e6a3d61a337c0f8b763ca1e8717c03b369e87a7ec7ce1319c0a",
-                "sha256:8f3cd2e254d8f793e7f3d6d9df77b92252b52637291d0f0da013c76ea2724b6c"
+                "sha256:30639c035cdb23534cd4aa2dd52c3bf48f06e5f4a941509c8bafd8ce11080259",
+                "sha256:8b74bedcbbbaca38ff6d7491d76f2b06b3592611af620f8426e82dddb04a5ced"
             ],
-            "version": "==1.14.0"
+            "version": "==1.15.0"
         },
         "toml": {
             "hashes": [
-                "sha256:229f81c57791a41d65e399fc06bf0848bab550a9dfd5ed66df18ce5f05e73d5c",
-                "sha256:235682dd292d5899d361a811df37e04a8828a5b1da3115886b73cf81ebc9100e"
+                "sha256:926b612be1e5ce0634a2ca03470f95169cf16f939018233a670519cb4ac58b0f",
+                "sha256:bda89d5935c2eac546d648028b9901107a595863cb36bae0c73ac804a9b4ce88"
             ],
-            "version": "==0.10.0"
+            "version": "==0.10.1"
         },
         "typed-ast": {
             "hashes": [
@@ -338,10 +348,10 @@
         },
         "wcwidth": {
             "hashes": [
-                "sha256:cafe2186b3c009a04067022ce1dcd79cb38d8d65ee4f4791b8888d6599d1bbe1",
-                "sha256:ee73862862a156bf77ff92b09034fc4825dd3af9cf81bc5b360668d425f3c5f1"
+                "sha256:79375666b9954d4a1a10739315816324c3e73110af9d0e102d906fdb0aec009f",
+                "sha256:8c6b5b6ee1360b842645f336d9e5d68c55817c26d3050f46b235ef2bc650e48f"
             ],
-            "version": "==0.1.9"
+            "version": "==0.2.4"
         },
         "wrapt": {
             "hashes": [
@@ -351,10 +361,11 @@
         },
         "zipp": {
             "hashes": [
-                "sha256:aa36550ff0c0b7ef7fa639055d797116ee891440eac1a56f378e2d3179e0320b",
-                "sha256:c599e4d75c98f6798c509911d08a22e6c021d074469042177c8c86fb92eefd96"
+                "sha256:c70410551488251b0fee67b460fb9a536af8d6f9f008ad10ac51f615b6a521b1",
+                "sha256:e0d9e63797e483a30d27e09fffd308c59a700d365ec34e93cc100844168bf921"
             ],
-            "version": "==3.1.0"
+            "index": "pypi",
+            "version": "==1.2.0"
         }
     }
 }