Add black and isort to pipenv dev dependencies

These do a very opinionated automatic formatting and validation of
code.

See: https://sourcery.ai/blog/python-best-practices/

Pipfile

@@ -8,6 +8,8 @@ pytest = "*"
 ipython = "*"
 flake8 = "*"
 pytest-clarity = "*"
+black = "*"
+isort = "*"
 
 [packages]
 pandas = "*"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "f8f0a9f208ec41f4d8183ecfc68356b40674b083b2f126c37468b3c9533ba5df"
+            "sha256": "0ad1012f267840ab6d1a2c5bec254013165b7f7ceb3a99eba7a316a0135a39eb"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -152,6 +152,13 @@
         }
     },
     "develop": {
+        "appdirs": {
+            "hashes": [
+                "sha256:9e5896d1372858f8dd3344faf4e5014d21849c756c8d5701f78f8a103b372d92",
+                "sha256:d8b24664561d0d34ddfaec54636d502d7cea6e29c3eaf68f3df6180863e2166e"
+            ],
+            "version": "==1.4.3"
+        },
         "atomicwrites": {
             "hashes": [
                 "sha256:03472c30eb2c5d1ba9227e4c2ca66ab8287fbfbbda3888aa93dc2e28fc6811b4",
@@ -173,6 +180,21 @@
             ],
             "version": "==0.1.0"
         },
+        "black": {
+            "hashes": [
+                "sha256:09a9dcb7c46ed496a9850b76e4e825d6049ecd38b611f1224857a79bd985a8cf",
+                "sha256:68950ffd4d9169716bcb8719a56c07a2f4485354fec061cdd5910aa07369731c"
+            ],
+            "index": "pypi",
+            "version": "==19.3b0"
+        },
+        "click": {
+            "hashes": [
+                "sha256:2335065e6395b9e67ca716de5f7526736bfa6ceead690adf616d925bdc622b13",
+                "sha256:5b94b49521f6456670fdb30cd82a4eca9412788a93fa6dd6df72c94d5a8ff2d7"
+            ],
+            "version": "==7.0"
+        },
         "decorator": {
             "hashes": [
                 "sha256:86156361c50488b84a3f148056ea716ca587df2f0de1d34750d35c21312725de",
@@ -218,6 +240,14 @@
             ],
             "version": "==0.2.0"
         },
+        "isort": {
+            "hashes": [
+                "sha256:54da7e92468955c4fceacd0c86bd0ec997b0e1ee80d97f67c35a78b719dccab1",
+                "sha256:6e811fcb295968434526407adb8796944f1988c5b65e8139058f2014cbe100fd"
+            ],
+            "index": "pypi",
+            "version": "==4.3.21"
+        },
         "jedi": {
             "hashes": [
                 "sha256:786b6c3d80e2f06fd77162a07fed81b8baa22dde5d62896a790a331d6ac21a27",
@@ -353,6 +383,13 @@
             ],
             "version": "==1.1.0"
         },
+        "toml": {
+            "hashes": [
+                "sha256:229f81c57791a41d65e399fc06bf0848bab550a9dfd5ed66df18ce5f05e73d5c",
+                "sha256:235682dd292d5899d361a811df37e04a8828a5b1da3115886b73cf81ebc9100e"
+            ],
+            "version": "==0.10.0"
+        },
         "traitlets": {
             "hashes": [
                 "sha256:9c4bd2d267b7153df9152698efb1050a5d84982d3384a37b2c1f7723ba3e7835",