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

def average_temperature(df):
    avg_temp_by_country = df.groupby(['countrry', 'decade'])['av_temp'].mean().reset_index()
    coldest_countries = avg_temp_by_country.sort_values('av_temp', ascending = True).head(20)
    coldest_countries_list = list(coldest_countries['country'])
    return avg_temp_by_country, coldest_countries_list