docs: def imfill(immsk):
      '''fill the empty patches of image mask 'immsk' '''
  
      for iz in range(immsk.shape[0]):
          for iy in range(immsk.shape[1]):
              ix0 = np.argmax(immsk[iz,iy,:]>0)
              ix1 = immsk.shape[2] - np.argmax(immsk[iz,iy,::-1]>0)
              if (ix1-ix0) > immsk.shape[2]-10: continue
              immsk[iz,iy,ix0:ix1] = 1
      return immsk