I have a df that has some columns and a multi-index with bytes datatype. to clean the columns I can do 

```
for c in df.columns:
    df[c] = df[c].apply(lambda x: x.decode('UTF-8'))

```

and for a single index this should work

```
df.index.map(lambda x: x.decode('UTF-8'))

```

But it appears to fail with multi-index. Is there anything similar I can do for the multi-index?

EDIT:
example

```
pd.DataFrame().from_dict({'val': {(b'A', b'a'): 1,
  (b'A', b'b'): 2,
  (b'B', b'a'): 3,
  (b'B', b'b'): 4,
  (b'B', b'c'): 5}})

```

and the desired output it 

```
pd.DataFrame().from_dict({'val': {('A', 'a'): 1,
  ('A', 'b'): 2,
  ('B', 'a'): 3,
  ('B', 'b'): 4,
  ('B', 'c'): 5}})

```