diff --git a/poetry.lock b/poetry.lock
index 47cfee3d26542ab27d3fcf5a83bc9ed217beb395..35bb1ce7a5f173329ea745332fb18eb502a2cd17 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -21,6 +21,14 @@ version = ">=1.0"
 python = "<3.7"
 version = ">=3.6.5"
 
+[[package]]
+category = "dev"
+description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
+name = "appdirs"
+optional = false
+python-versions = "*"
+version = "1.4.3"
+
 [[package]]
 category = "dev"
 description = "A few extensions to pyyaml."
@@ -32,15 +40,6 @@ version = "1.3.0"
 [package.dependencies]
 pyyaml = "*"
 
-[[package]]
-category = "dev"
-description = "Async generators and context managers for Python 3.5+"
-marker = "python_version == \"3.5\""
-name = "async-generator"
-optional = false
-python-versions = ">=3.5"
-version = "1.10"
-
 [[package]]
 category = "main"
 description = "Timeout context manager for asyncio programs"
@@ -81,6 +80,20 @@ optional = false
 python-versions = "*"
 version = "1.0.3"
 
+[[package]]
+category = "dev"
+description = "The uncompromising code formatter."
+name = "black"
+optional = false
+python-versions = ">=3.6"
+version = "18.9b0"
+
+[package.dependencies]
+appdirs = "*"
+attrs = ">=17.4.0"
+click = ">=6.5"
+toml = ">=0.9.4"
+
 [[package]]
 category = "main"
 description = "Foreign Function Interface for Python calling C code."
@@ -269,18 +282,6 @@ version = "19.0"
 pyparsing = ">=2.0.2"
 six = "*"
 
-[[package]]
-category = "dev"
-description = "Object-oriented filesystem paths"
-marker = "python_version < \"3.6\""
-name = "pathlib2"
-optional = false
-python-versions = "*"
-version = "2.3.3"
-
-[package.dependencies]
-six = "*"
-
 [[package]]
 category = "dev"
 description = "plugin and hook calling mechanisms for python"
@@ -409,10 +410,6 @@ wcwidth = "*"
 python = ">=2.8"
 version = ">=4.0.0"
 
-[package.dependencies.pathlib2]
-python = "<3.6"
-version = ">=2.2.0"
-
 [[package]]
 category = "dev"
 description = "Pytest support for asyncio."
@@ -424,10 +421,6 @@ version = "0.10.0"
 [package.dependencies]
 pytest = ">=3.0.6"
 
-[package.dependencies.async-generator]
-python = ">=3.5,<3.6"
-version = ">=1.3"
-
 [[package]]
 category = "dev"
 description = "Pytest plugin for measuring coverage."
@@ -538,18 +531,19 @@ python-versions = ">=2.7"
 version = "0.5.1"
 
 [metadata]
-content-hash = "33bcf6cbe26037e8d05e3cf8d1059fb43877cd613702b0b0fd3cb15eb321a709"
-python-versions = "^3.5.3"
+content-hash = "d83c7358271ca04f69123fda87374e1d82a4fea45a9c65b9ecc44acc905bdc57"
+python-versions = "^3.6"
 
 [metadata.hashes]
 aiohttp = ["00d198585474299c9c3b4f1d5de1a576cc230d562abc5e4a0e81d71a20a6ca55", "0155af66de8c21b8dba4992aaeeabf55503caefae00067a3b1139f86d0ec50ed", "09654a9eca62d1bd6d64aa44db2498f60a5c1e0ac4750953fdd79d5c88955e10", "199f1d106e2b44b6dacdf6f9245493c7d716b01d0b7fbe1959318ba4dc64d1f5", "296f30dedc9f4b9e7a301e5cc963012264112d78a1d3094cd83ef148fdf33ca1", "368ed312550bd663ce84dc4b032a962fcb3c7cae099dbbd48663afc305e3b939", "40d7ea570b88db017c51392349cf99b7aefaaddd19d2c78368aeb0bddde9d390", "629102a193162e37102c50713e2e31dc9a2fe7ac5e481da83e5bb3c0cee700aa", "6d5ec9b8948c3d957e75ea14d41e9330e1ac3fed24ec53766c780f82805140dc", "87331d1d6810214085a50749160196391a712a13336cd02ce1c3ea3d05bcf8d5", "9a02a04bbe581c8605ac423ba3a74999ec9d8bce7ae37977a3d38680f5780b6d", "9c4c83f4fa1938377da32bc2d59379025ceeee8e24b89f72fcbccd8ca22dc9bf", "9cddaff94c0135ee627213ac6ca6d05724bfe6e7a356e5e09ec57bd3249510f6", "a25237abf327530d9561ef751eef9511ab56fd9431023ca6f4803f1994104d72", "a5cbd7157b0e383738b8e29d6e556fde8726823dae0e348952a61742b21aeb12", "a97a516e02b726e089cffcde2eea0d3258450389bbac48cbe89e0f0b6e7b0366", "acc89b29b5f4e2332d65cd1b7d10c609a75b88ef8925d487a611ca788432dfa4", "b05bd85cc99b06740aad3629c2585bda7b83bd86e080b44ba47faf905fdf1300", "c2bec436a2b5dafe5eaeb297c03711074d46b6eb236d002c13c42f25c4a8ce9d", "cc619d974c8c11fe84527e4b5e1c07238799a8c29ea1c1285149170524ba9303", "d4392defd4648badaa42b3e101080ae3313e8f4787cb517efd3f5b8157eaefd6", "e1c3c582ee11af7f63a34a46f0448fca58e59889396ffdae1f482085061a2889"]
+appdirs = ["9e5896d1372858f8dd3344faf4e5014d21849c756c8d5701f78f8a103b372d92", "d8b24664561d0d34ddfaec54636d502d7cea6e29c3eaf68f3df6180863e2166e"]
 "aspy.yaml" = ["463372c043f70160a9ec950c3f1e4c3a82db5fca01d334b6bc89c7164d744bdc", "e7c742382eff2caed61f87a39d13f99109088e5e93f04d76eb8d4b28aa143f45"]
-async-generator = ["01c7bf666359b4967d2cda0000cc2e4af16a0ae098cbffcb8472fb9e8ad6585b", "6ebb3d106c12920aaae42ccb6f787ef5eefdcdd166ea3d628fa8476abe712144"]
 async-timeout = ["0c3c816a028d47f659d6ff5c745cb2acf1f966da1fe5c19c77a70282b25f4c5f", "4291ca197d287d274d0b6cb5d6f8f8f82d434ed288f962539ff18cc9012f9ea3"]
 atomicwrites = ["03472c30eb2c5d1ba9227e4c2ca66ab8287fbfbbda3888aa93dc2e28fc6811b4", "75a9445bac02d8d058d5e1fe689654ba5a6556a1dfd8ce6ec55a0ed79866cfa6"]
 attr = ["0b1aaddb85bd9e9c4bd75092f4440d6616ff40b0df0437f00771871670f7c9fd", "9091548058d17f132596e61fa7518e504f76b9a4c61ca7d86e1f96dbf7d4775d"]
 attrs = ["69c0dbf2ed392de1cb5ec704444b08a5ef81680a61cb899dc08127123af36a79", "f0b870f674851ecbfbbbd364d6b5cbdff9dcedbc7f3f5e18a6891057f21fe399"]
 base58 = ["1e42993c0628ed4f898c03b522b26af78fb05115732549b21a028bc4633d19ab", "6aa0553e477478993588303c54659d15e3c17ae062508c854a8b752d07c716bd", "9a793c599979c497800eb414c852b80866f28daaed5494703fc129592cc83e60"]
+black = ["817243426042db1d36617910df579a54f1afd659adb96fc5032fcf4b36209739", "e030a9a28f542debc08acceb273f228ac422798e5215ba2a791a6ddeaaca22a5"]
 cffi = ["041c81822e9f84b1d9c401182e174996f0bae9991f33725d059b771744290774", "046ef9a22f5d3eed06334d01b1e836977eeef500d9b78e9ef693f9380ad0b83d", "066bc4c7895c91812eff46f4b1c285220947d4aa46fa0a2651ff85f2afae9c90", "066c7ff148ae33040c01058662d6752fd73fbc8e64787229ea8498c7d7f4041b", "2444d0c61f03dcd26dbf7600cf64354376ee579acad77aef459e34efcb438c63", "300832850b8f7967e278870c5d51e3819b9aad8f0a2c8dbe39ab11f119237f45", "34c77afe85b6b9e967bd8154e3855e847b70ca42043db6ad17f26899a3df1b25", "46de5fa00f7ac09f020729148ff632819649b3e05a007d286242c4882f7b1dc3", "4aa8ee7ba27c472d429b980c51e714a24f47ca296d53f4d7868075b175866f4b", "4d0004eb4351e35ed950c14c11e734182591465a33e960a4ab5e8d4f04d72647", "4e3d3f31a1e202b0f5a35ba3bc4eb41e2fc2b11c1eff38b362de710bcffb5016", "50bec6d35e6b1aaeb17f7c4e2b9374ebf95a8975d57863546fa83e8d31bdb8c4", "55cad9a6df1e2a1d62063f79d0881a414a906a6962bc160ac968cc03ed3efcfb", "5662ad4e4e84f1eaa8efce5da695c5d2e229c563f9d5ce5b0113f71321bcf753", "59b4dc008f98fc6ee2bb4fd7fc786a8d70000d058c2bbe2698275bc53a8d3fa7", "73e1ffefe05e4ccd7bcea61af76f36077b914f92b76f95ccf00b0c1b9186f3f9", "a1f0fd46eba2d71ce1589f7e50a9e2ffaeb739fb2c11e8192aa2b45d5f6cc41f", "a2e85dc204556657661051ff4bab75a84e968669765c8a2cd425918699c3d0e8", "a5457d47dfff24882a21492e5815f891c0ca35fefae8aa742c6c263dac16ef1f", "a8dccd61d52a8dae4a825cdbb7735da530179fea472903eb871a5513b5abbfdc", "ae61af521ed676cf16ae94f30fe202781a38d7178b6b4ab622e4eec8cefaff42", "b012a5edb48288f77a63dba0840c92d0504aa215612da4541b7b42d849bc83a3", "d2c5cfa536227f57f97c92ac30c8109688ace8fa4ac086d19d0af47d134e2909", "d42b5796e20aacc9d15e66befb7a345454eef794fdb0737d1af593447c6c8f45", "dee54f5d30d775f525894d67b1495625dd9322945e7fee00731952e0368ff42d", "e070535507bd6aa07124258171be2ee8dfc19119c28ca94c9dfb7efd23564512", "e1ff2748c84d97b065cc95429814cdba39bcbd77c9c85c89344b317dc0d9cbff", "ed851c75d1e0e043cbf5ca9a8e1b13c4c90f3fbd863dacb01c0808e2b5204201"]
 cfgv = ["32edbe09de6f4521224b87822103a8c16a614d31a894735f7a5b3bcf0eb3c37e", "3bd31385cd2bebddbba8012200aaf15aa208539f1b33973759b4d02fc2148da5"]
 chardet = ["84ab92ed1c4d4f16916e05906b6b75a6c0fb5db821cc65e70cbd64a3e2a5eaae", "fc323ffcaeaed0e0a02bf4d117757b98aed530d9ed4531e3e15460124c106691"]
@@ -569,7 +563,6 @@ more-itertools = ["2112d2ca570bb7c3e53ea1a35cd5df42bb0fd10c45f0fb97178679c3c03d6
 multidict = ["024b8129695a952ebd93373e45b5d341dbb87c17ce49637b34000093f243dd4f", "041e9442b11409be5e4fc8b6a97e4bcead758ab1e11768d1e69160bdde18acc3", "045b4dd0e5f6121e6f314d81759abd2c257db4634260abcfe0d3f7083c4908ef", "047c0a04e382ef8bd74b0de01407e8d8632d7d1b4db6f2561106af812a68741b", "068167c2d7bbeebd359665ac4fff756be5ffac9cda02375b5c5a7c4777038e73", "148ff60e0fffa2f5fad2eb25aae7bef23d8f3b8bdaf947a65cdbe84a978092bc", "1d1c77013a259971a72ddaa83b9f42c80a93ff12df6a4723be99d858fa30bee3", "1d48bc124a6b7a55006d97917f695effa9725d05abe8ee78fd60d6588b8344cd", "31dfa2fc323097f8ad7acd41aa38d7c614dd1960ac6681745b6da124093dc351", "34f82db7f80c49f38b032c5abb605c458bac997a6c3142e0d6c130be6fb2b941", "3d5dd8e5998fb4ace04789d1d008e2bb532de501218519d70bb672c4c5a2fc5d", "4a6ae52bd3ee41ee0f3acf4c60ceb3f44e0e3bc52ab7da1c2b2aa6703363a3d1", "4b02a3b2a2f01d0490dd39321c74273fed0568568ea0e7ea23e02bd1fb10a10b", "4b843f8e1dd6a3195679d9838eb4670222e8b8d01bc36c9894d6c3538316fa0a", "5de53a28f40ef3c4fd57aeab6b590c2c663de87a5af76136ced519923d3efbb3", "61b2b33ede821b94fa99ce0b09c9ece049c7067a33b279f343adfe35108a4ea7", "6a3a9b0f45fd75dc05d8e93dc21b18fc1670135ec9544d1ad4acbcf6b86781d0", "76ad8e4c69dadbb31bad17c16baee61c0d1a4a73bed2590b741b2e1a46d3edd0", "7ba19b777dc00194d1b473180d4ca89a054dd18de27d0ee2e42a103ec9b7d014", "7c1b7eab7a49aa96f3db1f716f0113a8a2e93c7375dd3d5d21c4941f1405c9c5", "7fc0eee3046041387cbace9314926aa48b681202f8897f8bff3809967a049036", "8ccd1c5fff1aa1427100ce188557fc31f1e0a383ad8ec42c559aabd4ff08802d", "8e08dd76de80539d613654915a2f5196dbccc67448df291e69a88712ea21e24a", "c18498c50c59263841862ea0501da9f2b3659c00db54abfbf823a80787fde8ce", "c49db89d602c24928e68c0d510f4fcf8989d77defd01c973d6cbe27e684833b1", "ce20044d0317649ddbb4e54dab3c1bcc7483c78c27d3f58ab3d0c7e6bc60d26a", "d1071414dd06ca2eafa90c85a079169bfeb0e5f57fd0b45d44c092546fcd6fd9", "d3be11ac43ab1a3e979dac80843b42226d5d3cccd3986f2e03152720a4297cd7", "db603a1c235d110c860d5f39988ebc8218ee028f07a7cbc056ba6424372ca31b"]
 nodeenv = ["ad8259494cf1c9034539f6cced78a1da4840a4b157e23640bc4a0c0546b0cb7a"]
 packaging = ["0c98a5d0be38ed775798ece1b9727178c4469d9c3b4ada66e8e6b7849f8732af", "9e1cbf8c12b1f1ce0bb5344b8d7ecf66a6f8a6e91bcb0c84593ed6d3ab5c4ab3"]
-pathlib2 = ["25199318e8cc3c25dcb45cbe084cc061051336d5a9ea2a12448d3d8cb748f742", "5887121d7f7df3603bca2f710e7219f3eca0eb69e0b7cc6e0a022e155ac931a7"]
 pluggy = ["0825a152ac059776623854c1543d65a4ad408eb3d33ee114dff91e57ec6ae6fc", "b9817417e95936bf75d85d3f8767f7df6cdde751fc40aed3bb3074cbcb77757c"]
 pre-commit = ["92e406d556190503630fd801958379861c94884693a032ba66629d0351fdccd4", "cccc39051bc2457b0c0f7152a411f8e05e3ba2fe1a5613e4ee0833c1c1985ce3"]
 py = ["64f65755aee5b381cea27766a3a147c3f15b9b6b9ac88676de66ba2ae36793fa", "dc639b046a6e2cff5bbe40194ad65936d6ba360b52b3c3fe1d08a82dd50b5e53"]
diff --git a/pyproject.toml b/pyproject.toml
index 2dd0bb4b55d2fa7f7857dd7f3aa1b2135d516738..8990ec1f8be22067d084bfb41118e4fae290a3d7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,7 @@ pre-commit = "^1.16"
 pytest = "^4.6"
 pytest-cov = "^2.7"
 pytest-asyncio = "^0.10.0"
-#black = {version = "^18.3-alpha.0",allows-prereleases = true}
+black = {version = "^18.3-alpha.0",allows-prereleases = true}
 
 [build-system]
 requires = ["poetry>=0.12"]