docs: def _print_p(self):
          """
          m._print_p() -- Print probability (frequency) matrix
          """
          print "#  ",
          for i in range(self.width):
              print "  %4d   "%i,
          print
          for L in ['A', 'C', 'T', 'G']:
              print "#%s "%L,
              for i in range(self.width):
                  print  "%8.3f "%math.pow(2,self.logP[i][L]),
              print