I have a list of dataframes and I want to add a new column named 'new\_index' for each df in that list. The 'new\_index' is based on another list.

```
lst_dfs = [(pd.DataFrame({'country':['a','b','c','d'],
  'gdp':[1,2,3,4],
  'iso':['x','y','z','w']})),
  (pd.DataFrame({'country':['aa','bb','cc','dd'],
  'gdp':[11,22,33,44],
  'iso':['xx','yy','zz','ww']})),
  (pd.DataFrame({'country':['aaa','bbb','ccc','ddd'],
  'gdp':[111,222,333,444],
  'iso':['xxx','yyy','zzz','www']}))

lst_index = ['index1','index2','index3']

print(lst_dfs[0])
>>>
country gdp iso
0   a   1   x
1   b   2   y
2   c   3   z
3   d   4   w

```

Expected outputs:

```
country gdp iso new_index
0   a   1   x   index1
1   b   2   y   index1
2   c   3   z   index1
3   d   4   w   index1

country gdp iso new_index
0   aa  11  xx  index2
1   bb  22  yy  index2
2   cc  33  zz  index2
3   dd  44  ww  index2

country gdp iso new_index
0   aaa 111 xxx index3
1   bbb 222 yyy index3
2   ccc 333 zzz index3
3   ddd 444 www index3

```

Can anyone help me with the problem? Thanks so much.