Question: So I know how to get the sum of a single list so say, 

> 
> 
> > 
> > a=[1,2,3,4] 
> > 
> > 
> > sum(a)
> > 
> > 
> > 10
> > 
> > 
> > 
> 
> 
> 

How would I go about trying to sum lists in a list of lists? So, from: 

> 
> 
> > 
> > [[1,2],[2,3],[3,42]] to 
> > 
> > 
> > [3,5,45]?
> > 
> > 
> > 
> 
> 
>

Answer: 
You should use `sum()` in list comprehension for other lists

```
In [12]: a = [[1,2],[2,3],[3,42]]                                                                                                                                                                                                                             

In [13]: [sum(i) for i in a]                                                                                                                                                                                                                                  
Out[13]: [3, 5, 45]

```
```
intial_list = [[1,2],[2,3],[3,42]]
res = list(map(sum, intial_list))
print(res)

```

output

```
 [3,5,45]

```