I'm trying to sum arrays like vectors with

```
import numpy as np

def a_sum(array_list):
    array_sum = array_list[0]
    for i in range(len(array_list) - 1):
        array_sum = np.add(array_sum, array_list[i + 1])
    return array_sum

```

This functions is called many times which so i need to optimize it somehow. Is there a way?

Sample input-output:

```
In []: a_sum([[1,2],[3,4], [5,6]])
Out[]: array([ 9, 12])

```