docs: def reduce(self, sum1, sum2, *args):
          """
          The internal reduce function that sums the results from various
          processors
          """
          self.sum1g[...] += sum1
          if not self.pts_only: self.sum2g[...] += sum2
  
          if self.compute_mean_coords:
              N, centers_sum = args
              self.N[...] += N
              for i in range(self.bins.Ndim):
                  self.centers[i][...] += centers_sum[i]