Using the : syntax leads to non member attributes.

> If an attribute is defined in the class body with a type annotation
> but with no assigned value, a type checker should assume this is a non-member attribute

```
class Pet(Enum):
    genus: str  # Non-member attribute
    species: str  # Non-member attribute

    CAT = 1  # Member attribute
    DOG = 2  # Member attribute
```

https://typing.python.org/en/latest/spec/enums.html#defining-members