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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def subscribe(self, _func=None, needs=(), returns=(), modifies=(), **conditions):
 """Add a hook to a pangler. This method can either be used as a decorator for a function or method, or standalone on a callable. * `needs` is an iterable of parameters that this hook operates on. * `returns` is an iterable of parameters that this hook will modify and then pass back to the pangler. * `modifies` is a convenient way to specify that this hook both needs and returns a parameter. * The rest of the keyword arguments are parameter predicates. """


        modifies = set(modifies)
        parameters = set(needs) | modifies
        needs = parameters | set(conditions)
        if not needs:
            raise ValueError("tried to hook nothing")
        returns = set(returns) | modifies
        def deco(func):
            self.hooks.append(_Hook(
                func, needs, parameters, returns, conditions))
            return func

        # If we were passed a function as a positional parameter, then we
        # shouldn't behave like a decorator.
        if _func is not None:
            deco(_func)
        else:
            return deco