from typing import Dict


def is_class(cls_def: Dict) -> bool:
    """
    determine if JSON schema definition is for a class

    - JSON schema object can be differentiated as a python class object and not Dict using "additionalProperties"
    - "additionalProperties" is False for classes but is {type: <dictionary type here>} for dicts
    """
    return cls_def.get("type") == "object" and cls_def.get("additionalProperties", None) == False