What is the difference between __init__ and __call__?

The first is used to initialise newly created object, and receives arguments used to do that:

class Foo:
    def __init__(self, a, b, c):
        # ...

x = Foo(1, 2, 3) # __init__

The second implements function call operator.

class Foo:
    def __call__(self, a, b, c):
        # ...

x = Foo()
x(1, 2, 3) # __call__

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