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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 nfwPot(self, R, Rs, rho0, r_trunc):
 """ lensing potential of NFW profile :param R: radius of interest :type R: float/numpy array :param Rs: scale radius :type Rs: float :param rho0: density normalization (characteristic density) :type rho0: float :return: Epsilon(R) projected density at radius R """

        x = R / Rs
        tau = float(r_trunc) / Rs
        hx = self._h(x, tau)
        return 2 * rho0 * Rs ** 3 * hx