Module astrapy.utils.unset

# Copyright DataStax, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations


class UnsetType:
    _instance = None

    def __new__(cls) -> UnsetType:
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance

    def __repr__(self) -> str:
        return "(unset)"


_UNSET = UnsetType()