docs: def load_from_rho_file(self, filename):
          """Convenience function that loads two parameter sets from a rho.dat
          file, as used by CRMod for forward resistivity/phase models.
  
          Parameters
          ----------
          filename: string, file path
              filename of rho.dat file
  
          Returns
          -------
          cid_mag: int
              ID of magnitude parameter set
          cid_phase: int
              ID of phase parameter set
  
          """
          data = np.loadtxt(filename, skiprows=1)
          cid_mag = self.add_data(data[:, 0])
          cid_pha = self.add_data(data[:, 1])
          return cid_mag, cid_pha