Solve the programming task below in a Python markdown code block.
Complete the function that takes two integers (`a, b`, where `a < b`) and return an array of all integers between the input parameters, **including** them.

For example:
```
a = 1
b = 4
--> [1, 2, 3, 4]
```
Also feel free to reuse/extend the following starter code:
```python
def between(a,b):
```