docs: def pdf_mmd(self, lon, lat, mag_1, mag_2, distance_modulus, mask, delta_mag=0.03, steps=1000):
          """
          Ok, now here comes the beauty of having the signal MMD.
          """
          logger.info('Running MMD pdf')
   
          roi = mask.roi
          mmd = self.signalMMD(mask,distance_modulus,delta_mag=delta_mag,mass_steps=steps)
          
          # This is fragile, store this information somewhere else...
          nedges = np.rint((roi.bins_mag[-1]-roi.bins_mag[0])/delta_mag)+1
          edges_mag,delta_mag = np.linspace(roi.bins_mag[0],roi.bins_mag[-1],nedges,retstep=True)
                                      
          idx_mag_1 = np.searchsorted(edges_mag,mag_1)
          idx_mag_2 = np.searchsorted(edges_mag,mag_2)
   
          if np.any(idx_mag_1 > nedges) or np.any(idx_mag_1 == 0):
              msg = "Magnitude out of range..."
              raise Exception(msg)
          if np.any(idx_mag_2 > nedges) or np.any(idx_mag_2 == 0):
              msg = "Magnitude out of range..."
              raise Exception(msg)
   
          idx = mask.roi.indexROI(lon,lat)
          u_color = mmd[(mask.mask_roi_digi[idx],idx_mag_1,idx_mag_2)]
   
          # Remove the bin size to convert the pdf to units of mag^-2
          u_color /= delta_mag**2
   
          return u_color