code: def _compute_oneletter(self):
          
          letters = []
          for i in range(self.width):
              downcase = None
              if self.bits[i] < 0.25:
                  letters.append('.')
                  continue
              if self.bits[i] < 1.0: downcase = 'True'
              tups = [(self.ll[i][x],x) for x in ACGT if self.ll[i][x] > 0.0]
              if not tups:  #Kludge if all values are negative (can this really happen?)
                  tups = [(self.ll[i][x],x) for x in ACGT]
                  tups.sort()
                  tups.reverse()
                  tups = [tups[0]]
                  downcase = 'True'
              tups.sort()      #Rank by LL
              tups.reverse()
              bases = [x[1] for x in tups[0:2]]
              bases.sort()
              if len(bases) == 2: L = two2one[''.join(bases)]
              else:               L = bases[0]
              if downcase: L = L.lower()
              letters.append(L)
          self.oneletter = ''.join(letters)
docs: m._compute_oneletter() -- [utility] Set the oneletter member variable