# coding: utf-8

from setuptools import find_packages, setup

setup(
    packages=find_packages(),
    python_requires='~=3.7',
    extras_require={
        'dev': ['mypy', 'pytest'],
        'iscsi': ['cython-iscsi'],
        'sgio': ['cython-sgio'],
    },
)

# coding: utf-8

from setuptools import find_packages, setup

setup(
    packages=find_packages(),
    python_requires='~=3.7',
    extras_require={
        'dev': ['pytest'],
        'iscsi': ['cython-iscsi'],
        'sgio': ['cython-sgio'],
    },
)

--- 
+++ 
@@ -6,7 +6,7 @@
     packages=find_packages(),
     python_requires='~=3.7',
     extras_require={
-        'dev': ['pytest'],
+        'dev': ['mypy', 'pytest'],
         'iscsi': ['cython-iscsi'],
         'sgio': ['cython-sgio'],
     },
Add mypy to the development dependencies.

The code type-checks clean and this will allow keeping it so.
