diff --git a/poetry.lock b/poetry.lock
index 144ba43..0c64d0c 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -260,7 +260,7 @@ python-versions = ">=3.5"
 
 [[package]]
 name = "mypy"
-version = "0.812"
+version = "0.902"
 description = "Optional static typing for Python"
 category = "dev"
 optional = false
@@ -268,11 +268,13 @@ python-versions = ">=3.5"
 
 [package.dependencies]
 mypy-extensions = ">=0.4.3,<0.5.0"
-typed-ast = ">=1.4.0,<1.5.0"
+toml = "*"
+typed-ast = {version = ">=1.4.0,<1.5.0", markers = "python_version < \"3.8\""}
 typing-extensions = ">=3.7.4"
 
 [package.extras]
 dmypy = ["psutil (>=4.0)"]
+python2 = ["typed-ast (>=1.4.0,<1.5.0)"]
 
 [[package]]
 name = "mypy-extensions"
@@ -537,7 +539,7 @@ testing = ["pytest (>=3.5,!=3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6"
-content-hash = "6c81df97f71df0b1943655e63d79845dcb957d48e390c067572e15532c6f6b20"
+content-hash = "f1828e83f011d6e517c64225d2800a6bed3f8fa5e2c82b970b333f65ab0730f4"
 
 [metadata.files]
 appnope = [
@@ -668,28 +670,29 @@ more-itertools = [
     {file = "more_itertools-8.6.0-py3-none-any.whl", hash = "sha256:8e1a2a43b2f2727425f2b5839587ae37093f19153dc26c0927d1048ff6557330"},
 ]
 mypy = [
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-    {file = "mypy-0.812-cp35-cp35m-manylinux1_x86_64.whl", hash = "sha256:28fb5479c494b1bab244620685e2eb3c3f988d71fd5d64cc753195e8ed53df7c"},
-    {file = "mypy-0.812-cp35-cp35m-manylinux2010_x86_64.whl", hash = "sha256:9743c91088d396c1a5a3c9978354b61b0382b4e3c440ce83cf77994a43e8c521"},
-    {file = "mypy-0.812-cp35-cp35m-win_amd64.whl", hash = "sha256:d7da2e1d5f558c37d6e8c1246f1aec1e7349e4913d8fb3cb289a35de573fe2eb"},
-    {file = "mypy-0.812-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:4eec37370483331d13514c3f55f446fc5248d6373e7029a29ecb7b7494851e7a"},
-    {file = "mypy-0.812-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:d65cc1df038ef55a99e617431f0553cd77763869eebdf9042403e16089fe746c"},
-    {file = "mypy-0.812-cp36-cp36m-manylinux2010_x86_64.whl", hash = "sha256:61a3d5b97955422964be6b3baf05ff2ce7f26f52c85dd88db11d5e03e146a3a6"},
-    {file = "mypy-0.812-cp36-cp36m-win_amd64.whl", hash = "sha256:25adde9b862f8f9aac9d2d11971f226bd4c8fbaa89fb76bdadb267ef22d10064"},
-    {file = "mypy-0.812-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:552a815579aa1e995f39fd05dde6cd378e191b063f031f2acfe73ce9fb7f9e56"},
-    {file = "mypy-0.812-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:499c798053cdebcaa916eef8cd733e5584b5909f789de856b482cd7d069bdad8"},
-    {file = "mypy-0.812-cp37-cp37m-manylinux2010_x86_64.whl", hash = "sha256:5873888fff1c7cf5b71efbe80e0e73153fe9212fafdf8e44adfe4c20ec9f82d7"},
-    {file = "mypy-0.812-cp37-cp37m-win_amd64.whl", hash = "sha256:9f94aac67a2045ec719ffe6111df543bac7874cee01f41928f6969756e030564"},
-    {file = "mypy-0.812-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:d23e0ea196702d918b60c8288561e722bf437d82cb7ef2edcd98cfa38905d506"},
-    {file = "mypy-0.812-cp38-cp38-manylinux1_x86_64.whl", hash = "sha256:674e822aa665b9fd75130c6c5f5ed9564a38c6cea6a6432ce47eafb68ee578c5"},
-    {file = "mypy-0.812-cp38-cp38-manylinux2010_x86_64.whl", hash = "sha256:abf7e0c3cf117c44d9285cc6128856106183938c68fd4944763003decdcfeb66"},
-    {file = "mypy-0.812-cp38-cp38-win_amd64.whl", hash = "sha256:0d0a87c0e7e3a9becdfbe936c981d32e5ee0ccda3e0f07e1ef2c3d1a817cf73e"},
-    {file = "mypy-0.812-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:7ce3175801d0ae5fdfa79b4f0cfed08807af4d075b402b7e294e6aa72af9aa2a"},
-    {file = "mypy-0.812-cp39-cp39-manylinux1_x86_64.whl", hash = "sha256:b09669bcda124e83708f34a94606e01b614fa71931d356c1f1a5297ba11f110a"},
-    {file = "mypy-0.812-cp39-cp39-manylinux2010_x86_64.whl", hash = "sha256:33f159443db0829d16f0a8d83d94df3109bb6dd801975fe86bacb9bf71628e97"},
-    {file = "mypy-0.812-cp39-cp39-win_amd64.whl", hash = "sha256:3f2aca7f68580dc2508289c729bd49ee929a436208d2b2b6aab15745a70a57df"},
-    {file = "mypy-0.812-py3-none-any.whl", hash = "sha256:2f9b3407c58347a452fc0736861593e105139b905cca7d097e413453a1d650b4"},
-    {file = "mypy-0.812.tar.gz", hash = "sha256:cd07039aa5df222037005b08fbbfd69b3ab0b0bd7a07d7906de75ae52c4e3119"},
+    {file = "mypy-0.902-cp35-cp35m-macosx_10_9_x86_64.whl", hash = "sha256:3f12705eabdd274b98f676e3e5a89f247ea86dc1af48a2d5a2b080abac4e1243"},
+    {file = "mypy-0.902-cp35-cp35m-manylinux1_x86_64.whl", hash = "sha256:2f9fedc1f186697fda191e634ac1d02f03d4c260212ccb018fabbb6d4b03eee8"},
+    {file = "mypy-0.902-cp35-cp35m-manylinux2010_x86_64.whl", hash = "sha256:0756529da2dd4d53d26096b7969ce0a47997123261a5432b48cc6848a2cb0bd4"},
+    {file = "mypy-0.902-cp35-cp35m-win_amd64.whl", hash = "sha256:68a098c104ae2b75e946b107ef69dd8398d54cb52ad57580dfb9fc78f7f997f0"},
+    {file = "mypy-0.902-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:cd01c599cf9f897b6b6c6b5d8b182557fb7d99326bcdf5d449a0fbbb4ccee4b9"},
+    {file = "mypy-0.902-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:e89880168c67cf4fde4506b80ee42f1537ad66ad366c101d388b3fd7d7ce2afd"},
+    {file = "mypy-0.902-cp36-cp36m-manylinux2010_x86_64.whl", hash = "sha256:ebe2bc9cb638475f5d39068d2dbe8ae1d605bb8d8d3ff281c695df1670ab3987"},
+    {file = "mypy-0.902-cp36-cp36m-win_amd64.whl", hash = "sha256:f89bfda7f0f66b789792ab64ce0978e4a991a0e4dd6197349d0767b0f1095b21"},
+    {file = "mypy-0.902-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:746e0b0101b8efec34902810047f26a8c80e1efbb4fc554956d848c05ef85d76"},
+    {file = "mypy-0.902-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:0190fb77e93ce971954c9e54ea61de2802065174e5e990c9d4c1d0f54fbeeca2"},
+    {file = "mypy-0.902-cp37-cp37m-manylinux2010_x86_64.whl", hash = "sha256:b5dfcd22c6bab08dfeded8d5b44bdcb68c6f1ab261861e35c470b89074f78a70"},
+    {file = "mypy-0.902-cp37-cp37m-win_amd64.whl", hash = "sha256:b5ba1f0d5f9087e03bf5958c28d421a03a4c1ad260bf81556195dffeccd979c4"},
+    {file = "mypy-0.902-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:9ef5355eaaf7a23ab157c21a44c614365238a7bdb3552ec3b80c393697d974e1"},
+    {file = "mypy-0.902-cp38-cp38-manylinux1_x86_64.whl", hash = "sha256:517e7528d1be7e187a5db7f0a3e479747307c1b897d9706b1c662014faba3116"},
+    {file = "mypy-0.902-cp38-cp38-manylinux2010_x86_64.whl", hash = "sha256:fd634bc17b1e2d6ce716f0e43446d0d61cdadb1efcad5c56ca211c22b246ebc8"},
+    {file = "mypy-0.902-cp38-cp38-win_amd64.whl", hash = "sha256:fc4d63da57ef0e8cd4ab45131f3fe5c286ce7dd7f032650d0fbc239c6190e167"},
+    {file = "mypy-0.902-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:353aac2ce41ddeaf7599f1c73fed2b75750bef3b44b6ad12985a991bc002a0da"},
+    {file = "mypy-0.902-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:ae94c31bb556ddb2310e4f913b706696ccbd43c62d3331cd3511caef466871d2"},
+    {file = "mypy-0.902-cp39-cp39-manylinux1_x86_64.whl", hash = "sha256:8be7bbd091886bde9fcafed8dd089a766fa76eb223135fe5c9e9798f78023a20"},
+    {file = "mypy-0.902-cp39-cp39-manylinux2010_x86_64.whl", hash = "sha256:4efc67b9b3e2fddbe395700f91d5b8deb5980bfaaccb77b306310bd0b9e002eb"},
+    {file = "mypy-0.902-cp39-cp39-win_amd64.whl", hash = "sha256:9f1d74eeb3f58c7bd3f3f92b8f63cb1678466a55e2c4612bf36909105d0724ab"},
+    {file = "mypy-0.902-py3-none-any.whl", hash = "sha256:a26d0e53e90815c765f91966442775cf03b8a7514a4e960de7b5320208b07269"},
+    {file = "mypy-0.902.tar.gz", hash = "sha256:9236c21194fde5df1b4d8ebc2ef2c1f2a5dc7f18bcbea54274937cae2e20a01c"},
 ]
 mypy-extensions = [
     {file = "mypy_extensions-0.4.3-py2.py3-none-any.whl", hash = "sha256:090fedd75945a69ae91ce1303b5824f428daf5a028d2f6ab8a299250a846f15d"},
@@ -766,6 +769,8 @@ pyyaml = [
     {file = "PyYAML-5.3.1-cp37-cp37m-win_amd64.whl", hash = "sha256:73f099454b799e05e5ab51423c7bcf361c58d3206fa7b0d555426b1f4d9a3eaf"},
     {file = "PyYAML-5.3.1-cp38-cp38-win32.whl", hash = "sha256:06a0d7ba600ce0b2d2fe2e78453a470b5a6e000a985dd4a4e54e436cc36b0e97"},
     {file = "PyYAML-5.3.1-cp38-cp38-win_amd64.whl", hash = "sha256:95f71d2af0ff4227885f7a6605c37fd53d3a106fcab511b8860ecca9fcf400ee"},
+    {file = "PyYAML-5.3.1-cp39-cp39-win32.whl", hash = "sha256:ad9c67312c84def58f3c04504727ca879cb0013b2517c85a9a253f0cb6380c0a"},
+    {file = "PyYAML-5.3.1-cp39-cp39-win_amd64.whl", hash = "sha256:6034f55dab5fea9e53f436aa68fa3ace2634918e8b5994d82f3621c04ff5ed2e"},
     {file = "PyYAML-5.3.1.tar.gz", hash = "sha256:b8eac752c5e14d3eca0e6dd9199cd627518cb5ec06add0de9d32baeee6fe645d"},
 ]
 six = [
diff --git a/pyproject.toml b/pyproject.toml
index d6ef5ce..e83ae26 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -33,7 +33,7 @@ pygments = "^2.5.2"
 
 [tool.poetry.dev-dependencies]
 ipdb = "^0.13.2"
-mypy = "^0.812"
+mypy = "^0.902"
 flake8 = "^3.8.3"
 pytest = "^5.4.3"
 pytest-cov = "^2.10.0"