add flake8

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "5cf841925fa45f6b1c8fd6b5bd3829f5b02b81413815d3fa4755acb6c4132e2e"
+            "sha256": "439b60cb87b0180f0b78c531085f9bbeef7685ef038256f80b0a8123e7d144e6"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -297,5 +297,37 @@
             "version": "==2.0.1"
         }
     },
-    "develop": {}
+    "develop": {
+        "flake8": {
+            "hashes": [
+                "sha256:07528381786f2a6237b061f6e96610a4167b226cb926e2aa2b6b1d78057c576b",
+                "sha256:bf8fd333346d844f616e8d47905ef3a3384edae6b4e9beb0c5101e25e3110907"
+            ],
+            "index": "pypi",
+            "version": "==3.9.2"
+        },
+        "mccabe": {
+            "hashes": [
+                "sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42",
+                "sha256:dd8d182285a0fe56bace7f45b5e7d1a6ebcbf524e8f3bd87eb0f125271b8831f"
+            ],
+            "version": "==0.6.1"
+        },
+        "pycodestyle": {
+            "hashes": [
+                "sha256:514f76d918fcc0b55c6680472f0a37970994e07bbb80725808c17089be302068",
+                "sha256:c389c1d06bf7904078ca03399a4816f974a1d590090fecea0c63ec26ebaf1cef"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==2.7.0"
+        },
+        "pyflakes": {
+            "hashes": [
+                "sha256:7893783d01b8a89811dd72d7dfd4d84ff098e5eed95cfa8905b22bbffe52efc3",
+                "sha256:f5bc8ecabc05bb9d291eb5203d6810b49040f6ff446a756326104746cc00c1db"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==2.3.1"
+        }
+    }
 }