def METHOD_NAME(x1, x2, lengthscale, outputscale, lmc_coeffs):
    # RBF kernel function w/ Nystrom approximation
    # x1: ... x N x D
    # x2: ... x M x D
    # lengthscale: ... x 1 x D
    # outputscale: ...
    K_xx = _covar_func(x1, x2, lengthscale=lengthscale, outputscale=outputscale)
    return KroneckerProductLinearOperator(K_xx, RootLinearOperator(lmc_coeffs))