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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 architecture(self):
 """Returns a dictionary describing the architecture of the layer."""

        arch = {'class': self.__class__,
                'n_in': self.n_in,
                'n_units': self.n_units,
                'activation_function': self.activation_function
                if hasattr(self, 'activation_function') else None}
        return arch