Python での複数レベルの入れ子リストの再帰的処理方法 (推奨)

#!/usr/bin/env python
# -*- coding: utf-8 -*-


def unilist(ll):
  
  """
  功能:用递归方法删除多层列表中重复元素
  """
  
  result = []
  for i in ll:
    if isinstance(i, list):
      if unilist(i) not in result:
        result.append(unilist(i))
    else:
      if i not in result:
        result.append(i)
  return result


def flatten(ll):
  """
  功能:用递归方法展开多层列表,以生成器方式输出
  """
  if isinstance(ll, list):
    for i in ll:
      for element in flatten(i):
        yield element
  else:
    yield ll


testcase= ['and', 'B', ['not', 'A'],[1,2,1,[2,1],[1,1,[2,2,1]]], ['not', 'A', 'A'],['or', 'A', 'B' ,'A'] , 'B']

print unilist(testcase)

print list(flatten(testcase))