Your job is to return the volume of a cup when given the diameter of the top, the diameter of the bottom and the height.
You know that there is a steady gradient from the top to the bottom.
You want to return the volume rounded to 2 decimal places.
Exmples:
```python
cup_volume(1, 1, 1)==0.79
cup_volume(10, 8, 10)==638.79
cup_volume(1000, 1000, 1000)==785398163.4
cup_volume(13.123, 123.12, 1)==4436.57
cup_volume(5, 12, 31)==1858.51
```
You will only be passed positive numbers.
import math
def cup_volume(d1, d2, height):
    return round(math.pi * height * (d1**2 + d2**2 + d1*d2)/12, 2)
import math
def cup_volume(d1, d2, height):
    return round(math.pi * height * (d1**2 + d2**2 + d1*d2)/12, 2)