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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 initialize(self):
 """Initializes the network. Checks that no extra kwargs were passed to the constructor, and compiles the train, predict, and evaluation functions. Subsequent calls to this function will return without any action. """

        if getattr(self, '_initialized', False):
            return

        out = getattr(self, '_output_layers', None)
        if out is None:
            self.initialize_layers()
        self._check_for_unused_kwargs()

        iter_funcs = self._create_iter_funcs(
            self.layers_, self.objective, self.update,
            self.y_tensor_type,
            )
        self.train_iter_, self.eval_iter_, self.predict_iter_ = iter_funcs
        self._initialized = True