code: def _call(self, x):
          
          y = np.bincount(self._indices_flat, weights=x,
                          minlength=self.range.size)
  
          out = y.reshape(self.range.shape)
  
          if self.variant == 'dirac':
              weights = getattr(self.range, 'cell_volume', 1.0)
          elif self.variant == 'char_fun':
              weights = 1.0
          else:
              raise RuntimeError('The variant "{!r}" is not yet supported'
                                 ''.format(self.variant))
  
          if weights != 1.0:
              out /= weights
  
          return out
docs: Sum all values if indices are given multiple times.