Determine the type of function: class definition OR function (and what kind)
https://stackoverflow.com/questions/30758961/how-to-check-if-a-variable-is-an-es6-class-declaration/69316645#69316645
any
'Function' | 'GeneratorFunction' | 'AsyncFunction' | 'AsyncGeneratorFunction' | 'ArrowFunction' | 'class' | undefined
Determine the type of function: class definition OR function (and what kind)
https://stackoverflow.com/questions/30758961/how-to-check-if-a-variable-is-an-es6-class-declaration/69316645#69316645