I wouldn't be asking the question here, if I knew how to write for search engine. So do not blame me.
Met equal unknown syntax (https://habr.com/company/binarydistrict/blog/422409/):
def __new__(mcs, name, bases, attrs):
cls: 'BasePlugin' = super().__new__(mcs, name, bases, attrs)
The second line is incomprehensible to part with
Please suggest what it is.