So I'm trying to concatenate a string to a list, but for some reason it only works for the very last values:

```
labels_and_sents = []
for l in labels:
    for s in sents:
        sl = [l] + s

 labels_and_sents.append(sl)

```

Input:

```
labels = ['1','2','3']
sents = [['hi hello'], ['i was there'], ['this is a sent']]

```

Output:

```
[['3', 'this is a sent']]

```

What i need is:

```
[['1', 'hi hello'],['2', 'i was there'],['3', 'this is a sent']]

```