Shared via mypy Playground

main.py

class Person():
    def __init__(self, name: str, age: int, characteristics: type):
      self.name = name
      self.age = age
      self.characteristics = characteristics

def foo(person: Person) -> None:
    reveal_type(person.characteristics) # N: Revealed type is "builtins.type"
    class Sub(person.characteristics): pass