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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 calc_nfw(self, rbins, offsets=None, numTh=200, numRoff=200, numRinner=20, factorRouter=3):
 """Calculates Sigma and DeltaSigma profiles. Generates the surface mass density (sigma_nfw attribute of parent object) and differential surface mass density (deltasigma_nfw attribute of parent object) profiles of each cluster, assuming a spherical NFW model. Optionally includes the effect of cluster miscentering offsets. Parameters rbins : array_like Radial bins (in Mpc) for calculating cluster profiles. Should be 1D, optionally with astropy.units of Mpc. offsets : array_like, optional Parameter describing the width (in Mpc) of the Gaussian distribution of miscentering offsets. Should be 1D, optionally with astropy.units of Mpc. Other Parameters numTh : int, optional Parameter to pass to SurfaceMassDensity(). Number of bins to use for integration over theta, for calculating offset profiles (no effect for offsets=None). Default 200. numRoff : int, optional Parameter to pass to SurfaceMassDensity(). Number of bins to use for integration over R_off, for calculating offset profiles (no effect for offsets=None). Default 200. numRinner : int, optional Parameter to pass to SurfaceMassDensity(). Number of bins at r < min(rbins) to use for integration over Sigma(<r), for calculating DeltaSigma (no effect for Sigma ever, and no effect for DeltaSigma if offsets=None). Default 20. factorRouter : int, optional Parameter to pass to SurfaceMassDensity(). Factor increase over number of rbins, at min(r) < r < max(r), of bins that will be used at for integration over Sigma(<r), for calculating DeltaSigma (no effect for Sigma, and no effect for DeltaSigma if offsets=None). Default 3. """

        if offsets is None:
            self._sigoffset = np.zeros(self.number) * units.Mpc
        else:
            self._sigoffset = utils.check_units_and_type(offsets, units.Mpc,
                                                         num=self.number)

        self.rbins = utils.check_units_and_type(rbins, units.Mpc)

        rhoc = self._rho_crit.to(units.Msun / units.pc**2 / units.Mpc)
        smd = SurfaceMassDensity(self.rs, self.delta_c, rhoc,
                                 offsets=self._sigoffset,
                                 rbins=self.rbins,
                                 numTh=numTh,
                                 numRoff=numRoff,
                                 numRinner=numRinner,
                                 factorRouter=factorRouter)

        self.sigma_nfw = smd.sigma_nfw()
        self.deltasigma_nfw = smd.deltasigma_nfw()