code: def loop_cont_label(self, loop_type):
          
          for i in range(len(self.LOOPS) - 1, -1, -1):
              if loop_type == self.LOOPS[i][0]:
                  return self.LOOPS[i][2]
  
          raise InvalidLoopError(loop_type)
docs: Returns the label for the given loop type which
          continues the loop. loop_type must be one of 'FOR', 'WHILE', 'DO'