code: def _initializeTRNToRelayCellConnections(self):
      
      for x in range(self.relayWidth):
        for y in range(self.relayHeight):
  
          # Create one dendrite for each trn cell that projects to this relay cell
          # This dendrite contains one synapse corresponding to this TRN->relay
          # connection.
          relayCellIndex = self.relayCellIndex((x,y))
          trnCells = self._preSynapticTRNCells(x, y)
          for trnCell in trnCells:
            newSegment = self.relayConnections.createSegments([relayCellIndex])
            self.relayConnections.growSynapses(newSegment,
                                               [self.trnCellIndex(trnCell)], 1.0)
docs: Initialize TRN to relay cell connectivity. For each relay cell, create a
      dendritic segment for each TRN cell it connects to.