code: def ssd(p1, p2):
      
      return 2 - np.sum([(a-b)**2 for a,b in zip(p1,p2)])
docs: Calculates motif position similarity based on sum of squared distances.
      
      Parameters
      ----------
      p1 : list
          Motif position 1.
      
      p2 : list
          Motif position 2.
      
      Returns
      -------
      score : float