code: def dist(self, src, tar):
          
          if tar == src:
              return 0.0
          if not src or not tar:
              return 1.0
  
          max_length = max(len(src), len(tar))
  
          return self.dist_abs(src, tar) / max_length
docs: Return the normalized bag distance between two strings.
  
          Bag distance is normalized by dividing by :math:`max( |src|, |tar| )`.
  
          Parameters
          ----------
          src : str
              Source string for comparison
          tar : str
              Target string for comparison
  
          Returns
          -------
          float
              Normalized bag distance
  
          Examples
          --------
          >>> cmp = Bag()
          >>> cmp.dist('cat', 'hat')
          0.3333333333333333
          >>> cmp.dist('Niall', 'Neil')
          0.4
          >>> cmp.dist('aluminum', 'Catalan')
          0.625
          >>> cmp.dist('ATCG', 'TAGC')
          0.0