code/final.py contains unused variables/func call

```
def compare_countries(left_country, right_country):
    '''
    Compare average surface temperatures for two countries over time.
    '''
    left_data = get_country_temperatures(left_country)
    right_data = get_country_temperatures(right_country)
```

`left_data` and `right_data` are never used, leaving spurious requests to the web service
