Interview Course Based on Story Questions

# Problem statement
In this problem, you are provided with two lists of intervals. Each list contains a **disjoint** and intervals. Your job is to find the intersection of these lists of intervals. 

## Input
The input is two lists of intervals. Each list contains nested lists that have two integers representing the starting and ending points of the interval. The following is an example input:
```python3
[[1, 3], [5, 6], [7, 9]]
[[2, 4], [6, 7], [8, 10]]
```
## Output
The output is a list that contains the intervals' intersection. The following is an example output:
```
[[2, 3], [8, 9]]
```

# Coding exercise
You need to implement the function `intervals_intersection(intervals_a, intervals_b)`, where `intervals_a` and `intervals_b` are the lists of intervals. The function returns a list of intervals that contain the intervals' intersection.