> Hell, python type annotations were only introduced in python 3.5

Mypy was introduced with support for both for Python 2.x and 3.x (3.2 was the current) using type comments before Python introduced a standard way of using Python 3.0’s annotation syntax for typing; even when type annotations were added to Python proper, some uses now supported by them were left to mypy-style type comments in PEP 484/Python 3.5, with type annotations for variables added in PEP 526/Python 3.6.