default: str
    description: Optional[str] = None


class Server(BaseModelWithConfig):
    url: Union[AnyUrl, str]
    description: Optional[str] = None
    variables: Optional[dict[str, ServerVariable]] = None


class Reference(BaseModel):
    ref: str = Field(alias="$ref")


class Discriminator(BaseModel):
    propertyName: str

This means that now, if you set a value in a context variable before `yield`, the value would still be available after `yield` (as you would intuitively expect). And it also means that you can reset the context variable with a token afterwards.

For example, this works correctly now:

```Python
from contextvars import ContextVar