code: def rhyme_scheme(self):
          
          rhymes = dict()
          i = 64
          strs = ""
  
          for line in self.syllabified:
  
              w = line[-1][-1][-3:]
  
              for r in rhymes.keys():
                  if r.endswith(w) or w.endswith(r):
                      rhymes[w] = rhymes[r]
                      break
  
              if w in rhymes:
                  strs += rhymes[w]
              else:
                  i += 1
                  rhymes[w] = chr(i)
                  strs += chr(i)
  
          return strs
docs: Calculates the rhyme scheme of a given stanza. It doesn't yet support
          phonetical rhyming (homophones) and thus is still error-prone
  
          Example:
              >>> stanza = ['Ein rîchiu küneginne, frou Uote ir muoter hiez.', 'ir vater der hiez Dancrât, der in diu erbe liez', 'sît nâch sîme lebene, ein ellens rîcher man,', 'der ouch in sîner jugende grôzer êren vil gewan.']
              
              >>> S = Verse(stanza)
              
              >>> S.rhyme_scheme()
              'AABB'