code: def ic_pos(self, row1, row2=None):
          
          if row2 is None:
              row2 = [0.25,0.25,0.25,0.25]
  
          score = 0
          for a,b in zip(row1, row2):
              if a > 0:
                  score += a * log(a / b) / log(2)
          return score
docs: Calculate the information content of one position.
  
          Returns
          -------
          score : float
              Information content.