Question: 

Create a function that calculates acceleration given initial velocity v1, final velocity v2, start time t1, and end time t2. The formula for acceleration is:

To test your solution, call the function by inputting values 0, 10, 0, 20 for v1, v2, t1, and t2, respectively, and you should get the expected output.

Expected output:

0.5

Hint 1: Your function definition should have four parameters.

Hint 2: The acceleration formula inside the function would look like a = (v2 - v1) / (t2 - t1) .