dt_field: safe_datetime

    instance = MyDict(dt_field=safe_datetime.now())

    encoded_instance = jsonable_encoder(
        instance, custom_encoder={safe_datetime: lambda o: o.strftime("%H:%M:%S")}
    )
    assert encoded_instance["dt_field"] == instance["dt_field"].strftime("%H:%M:%S")

    encoded_instance = jsonable_encoder(
        instance, custom_encoder={datetime: lambda o: o.strftime("%H:%M:%S")}
    )

        if type(obj) in custom_encoder:
            return custom_encoder[type(obj)](obj)
        else:
            for encoder_type, encoder_instance in custom_encoder.items():
                if isinstance(obj, encoder_type):
                    return encoder_instance(obj)
    if include is not None and not isinstance(include, (set, dict)):
        include = set(include)