code: def dist_abs(self, src, tar):
          
          if src == tar:
              return 6
          if src == '' or tar == '':
              return 0
          src = list(mra(src))
          tar = list(mra(tar))
  
          if abs(len(src) - len(tar)) > 2:
              return 0
  
          length_sum = len(src) + len(tar)
          if length_sum < 5:
              min_rating = 5
          elif length_sum < 8:
              min_rating = 4
          elif length_sum < 12:
              min_rating = 3
          else:
              min_rating = 2
  
          for _ in range(2):
              new_src = []
              new_tar = []
              minlen = min(len(src), len(tar))
              for i in range(minlen):
                  if src[i] != tar[i]:
                      new_src.append(src[i])
                      new_tar.append(tar[i])
              src = new_src + src[minlen:]
              tar = new_tar + tar[minlen:]
              src.reverse()
              tar.reverse()
  
          similarity = 6 - max(len(src), len(tar))
  
          if similarity >= min_rating:
              return similarity
          return 0
docs: Return the MRA comparison rating of two strings.
  
          Parameters
          ----------
          src : str
              Source string for comparison
          tar : str
              Target string for comparison
  
          Returns
          -------
          int
              MRA comparison rating
  
          Examples
          --------
          >>> cmp = MRA()
          >>> cmp.dist_abs('cat', 'hat')
          5
          >>> cmp.dist_abs('Niall', 'Neil')
          6
          >>> cmp.dist_abs('aluminum', 'Catalan')
          0
          >>> cmp.dist_abs('ATCG', 'TAGC')
          5