For a pandas dataframe:

```
Name:        Tags:
'One'        ['tag1', 'tag3']
'Two'        []
'Three'      ['tag1']

```

How can 'tag2' be appended to the tags lists?

I have tried the following (addtag2 is another df):

```
df['Tags'] = df['Tags'].astype(str) + ', ' + addtag2['Tags'].astype(str)

```

and

```
df['Tags'] = df['Tags'].add(addtag2['Tags'].astype(str))

```

But they append the string outside the list eg *['tag1'], tag2 or ['tag1']tag2*

The desired output would be:

```
Name:        Tags:
'One'        ['tag1', 'tag3', 'tag2']
'Two'        ['tag2']
'Three'      ['tag1', 'tag2']

```