I have this code where i am trying to do list comprehension on `data` :

```
with open('data.csv') as csvfile:
    data = csv.reader(csvfile, delimiter=' ')
    data1 = [x.replace('.', '-') for x in data] 

```

but for some reason `AttributeError: 'list' object has no attribute 'replace'` How can i fix this?

data.csv has

```
MMM
ABT
ABBV
ABMD
ACN
ATVI
ADBE
AMD
AAP
AES
AMG
AFL
A
APD
AKAM
ALK
ALB

```