Refactor - functional programming

[ethanstrominger]

Change

self._calculate_balance_point_and_ua(
            initial_balance_point_sensitivity,
            stdev_pct_max,
            max_stdev_pct_diff,
            next_balance_point_sensitivity,
        )

=>

{   balance_point, stdev_pct
                balance_point_graph } =
             _get_graph (initial_balance_point_sensitivity,
            stdev_pct_max,
            max_stdev_pct_diff,
            next_balance_point_sensitivity,
            bills_winter)

[stemgene]

We found inside this if statement:

if (
                # the outlier has been removed
                new_stdev_pct - stdev_pct_i
                < max_stdev_pct_diff
            ):  # if it's a small enough change
                # add the outlier back in
                self.winter_processed_energy_bills.append(
                    outlier
                )  # then it's not worth removing it, and we exit
                outlier.eliminated_as_outlier = False
                break  # may want some kind of warning to be raised as well
            else:
                self.uas, avg_ua, stdev_pct = uas_i, avg_ua_i, stdev_pct_i

The values of avg_ua and stdev_pct didn't affect the pytest, even after deleting the else part. Moreover, the self.uas has just been defined but not been used ever.