code: def _hierarchical_adj_mat(self):
      mat_accumulate = np.triu(self._adj_mat)
      mat_distribute = np.tril(self._adj_mat)
      col_sums = mat_distribute.sum(axis=0)
      mat_distribute[:, col_sums > 0] = mat_distribute[
          :, col_sums > 0
      ] / mat_distribute[:, col_sums > 0].sum(axis=0, keepdims=True)
      I = np.eye(mat_accumulate.shape[0])
  
      return (mat_accumulate + mat_distribute + I) / 3.0
  
imports: from typing import Iterator, List
  import numpy
  import pandas
  from gluonts.core.component import validated
  from gluonts.model.forecast import SampleForecast
  from gluonts.mx import Tensor
label_desc: Use image node_id 3 for calling the TemporalHierarchy obj's underlying member method code with example usage: obj._hierarchical_adj_mat() and returns: unknown