There is a df Pandas dataframe: date av_temp deviations country year decade 577457 2013-05-01 19.059 1.022 Zimbabwe 2013 2010-2020 577458 2013-06-01 17.613 0.473 Zimbabwe 2013 2010-2020 577459 2013-07-01 17.000 0.453 Zimbabwe 2013 2010-2020 577460 2013-08-01 19.759 0.717 Zimbabwe 2013 2010-2020 Write a function that: 1) calculates the average temperature in countries (average av_temp by decade column grouped by country) 2) build a list of the 20 coldest countries in ascending av_temp order

import pandas as pd

# function that: calculate the average temperature in countries
def average_temp_of_country(df):
    return df.groupby('country')['av_temp'].mean()

# function that: build a list of the 20 coldest countries in ascending av_temp order
def coldest_20_countries(df):
    return df.groupby('country')['av_temp'].mean().sort_values()[:20]