Allocating random values from a list to missing column values, in Python

I have a two column dataframe

id  content

1    100
2    101  
3
4    100
5
6    104

Now for missing values of content , I want to randomly assign content from the list of plausible values content_list=range(100,111)

So for id=3 and id=5 I want to populate content by any random value from content_list.

I used random.choice, but missing something here:

def f(list):
   return random.choice(list)

if data.content.isnull():
    data['content']=data['content'].map(f,content_list)