# from typing import TypeVar, Union, _SpecialForm, _type_check


class Error:
    def __init__(self, message):
        self.message = message


# T = TypeVar("T")
# @_SpecialForm
# def Result(self, parameters):
#    """Result type.
#
#    Result[T] is equivalent to Union[T, Error].
#    """
#    arg = _type_check(parameters, f"{self} requires a single type.")
#    return [arg, Error]


def is_ok(obj) -> bool:
    return not isinstance(obj, Error)