Python None is an object (and a singleton)

singleton.py

# None is of type NoneType
print(f"{None} is of type", type(None))

# Each object contains a reference to its class,
# let's use this to create a new instance of NoneType
NewNone = None.__class__()

# NoneType is a *singleton*, so should be equal
assert NewNone is None

# Can we set attributes on None?
try:
    None.ok = True  # can't set attributes on None
except AttributeError as e:
    print(f"Can't set attribute on {None}:", e)

# Let's emulate NoneType, a singleton!
class EmptyType:
    __slots__ = ()  # no declared instance attributes permitted

    def __new__(cls, *args, **kwargs):
        if not hasattr(cls, "_instance"):
            cls._instance = super().__new__(cls, *args, **kwargs)

        return cls._instance  # will be 'self' in instance context

    def __str__(self):
        return "Empty"

    __repr__ = __str__


# With None being an instance of NoneType,
# so will Empty be an instance of EmptyType
Empty = EmptyType()

# Empty is of type EmptyType
print(f"{Empty} is of type", type(Empty))

# A new instance of EmptyType
MyEmpty = EmptyType()  #  could also have called Empty.__class__()

# EmptyType is a *singleton*, should be equal
assert MyEmpty is Empty

# Can we set attributes on Empty?
try:
    Empty.ok = True  # will fail because of __slots__
except AttributeError as e:
    print(f"Can't set attribute on {Empty}:", e)

# But _instance attribute was set, let's modify!
try:
    Empty._instance = "Hey there!"  # is read-only
except AttributeError as e:
    print(f"Can't change '_instance' of {Empty}:", e)


# NoneType is not a base type (i.e. not subclassable),
# but given the above we could do ...
class MyNoneType:
    def __new__(cls, *args, **kwargs):
        return None  # will be 'self' in instance context


# New instance!
MyNone = MyNoneType()

# Will be of type *type*, which we could subclass (if we´d like)
print(f"{MyNone} is of type", type(MyNoneType))

# MyNone is a None, hence a *singleton* (NoneType), and should be equal
assert MyNone is None

# Now also try this with True and False (also objects and singletons)