code: def dist(self, src, tar):
          
          if src == tar:
              return 0.0
          return self.dist_abs(src, tar) / (len(src) + len(tar))
docs: Return the normalized indel distance between two strings.
  
          This is equivalent to normalized Levenshtein distance, when only
          inserts and deletes are possible.
  
          Parameters
          ----------
          src : str
              Source string for comparison
          tar : str
              Target string for comparison
  
          Returns
          -------
          float
              Normalized indel distance
  
          Examples
          --------
          >>> cmp = Indel()
          >>> round(cmp.dist('cat', 'hat'), 12)
          0.333333333333
          >>> round(cmp.dist('Niall', 'Neil'), 12)
          0.333333333333
          >>> round(cmp.dist('Colin', 'Cuilen'), 12)
          0.454545454545
          >>> cmp.dist('ATCG', 'TAGC')
          0.5