code: def example_df():
      
      country_names = ['Germany',
                       'France',
                       'Indonesia',
                       'Ireland',
                       'Spain',
                       'Vatican']
      population = [82521653, 66991000, 255461700, 4761865, 46549045, None]
      population_time = [dt.datetime(2016, 12, 1),
                         dt.datetime(2017, 1, 1),
                         dt.datetime(2017, 1, 1),
                         None,  # Ireland
                         dt.datetime(2017, 6, 1),  # Spain
                         None,
                         ]
      euro = [True, True, False, True, True, True]
      df = pd.DataFrame({'country': country_names,
                         'population': population,
                         'population_time': population_time,
                         'EUR': euro})
      df = df[['country', 'population', 'population_time', 'EUR']]
      return df
docs: Create an example dataframe.