code: def get_shear_vel(self, saturated):
          
          try:
              if saturated:
                  return np.sqrt(self.g_mod / self.unit_sat_mass)
              else:
                  return np.sqrt(self.g_mod / self.unit_dry_mass)
          except TypeError:
              return None
docs: Calculate the shear wave velocity
  
          :param saturated: bool, if true then use saturated mass
          :return: