code: def get_total_spatial_integral(self, z=None):  
          
  
          if isinstance( z, u.Quantity):
              z = z.value
          return np.ones_like( z )
docs: Returns the total integral (for 2D functions) or the integral over the spatial components (for 3D functions).
          needs to be implemented in subclasses.
  
          :return: an array of values of the integral (same dimension as z).