code: def used_labels(self):
          
          result = []
  
          tmp = self.asm.strip(' \n\r\t')
          if not len(tmp) or tmp[0] in ('#', ';'):
              return result
  
          try:
              tmpLexer = asmlex.lex.lex(object=asmlex.Lexer(), lextab='zxbasmlextab')
              tmpLexer.input(tmp)
  
              while True:
                  token = tmpLexer.token()
                  if not token:
                      break
  
                  if token.type == 'ID':
                      result += [token.value]
          except:
              pass
  
          return result
docs: Returns a list of required labels for this instruction