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from .__version__ import __version__
try:
# python3 renamed copy_reg to copyreg
import copyreg
except ImportError:
import copy_reg as copyreg
class Sentinel(object):
_existing_instances = {}
def __init__(self, name):
super(Sentinel, self).__init__()
self._name = name
self._existing_instances[self._name] = self
def __repr__(self):
return f"<{self._name}>"
def __getnewargs__(self):
return (self._name,)
def __new__(
cls, name, obj_id=None
): # obj_id is for compatibility with previous versions pylint: disable=W0613
existing_instance = cls._existing_instances.get(name)
if existing_instance is not None:
return existing_instance
return super(Sentinel, cls).__new__(cls)
def _sentinel_unpickler(
name, obj_id=None
): # obj_id is for compat. with prev. versions pylint: disable=W0613
if name in Sentinel._existing_instances:
return Sentinel._existing_instances[name]
return Sentinel(name)
def _sentinel_pickler(sentinel):
return _sentinel_unpickler, sentinel.__getnewargs__()
copyreg.pickle(Sentinel, _sentinel_pickler, _sentinel_unpickler)
NOTHING = Sentinel("NOTHING")
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