Session02

@violetcontamination I will echo what @jefrailey has to say here.  Think about which function represents the more general case of a particular problem, and then you can make functions for more specific cases *in terms of* the more general function:

```python

def sum_series(n, x, y):
    # code here

def fibonacci(n):
    return sum_series(n, 0, 1)
```