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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 _separable_approx2(h, N=1):
 """ returns the N first approximations to the 2d function h whose sum should be h """

    return np.cumsum([np.outer(fy, fx) for fy, fx in _separable_series2(h, N)], 0)