A metaclass overrides __call__. When you then instantiate a class that uses this metaclass, at what point does the metaclass's __call__ intervene relative to the instance's __new__ and __init__?
class Singleton(type):
_i = {}
def __call__(cls, *a, **k):
if cls not in cls._i:
cls._i[cls] = super().__call__(*a, **k)
return cls._i[cls]