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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 h(self):
 r""" Returns the step size to be used in numerical differentiation with respect to the model parameters. The step size is given as a vector with length ``n_modelparams`` so that each model parameter can be weighted independently. """

        if np.size(self._h) > 1:
            assert np.size(self._h) == self.n_modelparams
            return self._h
        else:
            return self._h * np.ones(self.n_modelparams)