code: def updateRow(self, row, distribution):
      
      self.grow(row+1, len(distribution))
      self.hist_.axby(row, 1, 1, distribution)
      self.rowSums_[row] += distribution.sum()
      self.colSums_ += distribution
      self.hack_ = None
docs: Add distribution to row row.
      Distribution should be an array of probabilities or counts.
  
      :param row:   Integer index of the row to add to.
                    May be larger than the current number of rows, in which case
                    the histogram grows.
      :param distribution: Array of length equal to the number of columns.