<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default(self, value):
 """ Handle UUID, datetime, and callables. :param value: Value to encode """

        if isinstance(value, uuid.UUID):
            return str(value)
        elif isinstance(value, datetime.datetime):
            return value.isoformat()
        elif callable(value):
            return str(value)
        return json.JSONEncoder.default(self, value)