code: def numberOfProximalSynapses(self, cells=None):
      
      if cells is None:
        cells = xrange(self.numberOfCells())
  
      n = 0
      for cell in cells:
        n += self.proximalPermanences.nNonZerosOnRow(cell)
      return n
docs: Returns the number of proximal synapses with permanence>0 on these cells.
  
      Parameters:
      ----------------------------
      @param  cells (iterable)
              Indices of the cells. If None return count for all cells.