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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_index():
 """Load information from the data directory Returns ------- A namedtuple with three fields: nationalities cities countries """


    nationalities = read_table(get_data_path('nationalities.txt'), sep=':')

    # parse http://download.geonames.org/export/dump/countryInfo.txt
    countries = read_table(
        get_data_path('countryInfo.txt'), usecols=[4, 0], skip=1)

    # parse http://download.geonames.org/export/dump/cities15000.zip
    cities = read_table(get_data_path('cities15000.txt'), usecols=[1, 8])

    # load and apply city patches
    city_patches = read_table(get_data_path('citypatches.txt'))
    cities.update(city_patches)

    Index = namedtuple('Index', 'nationalities cities countries')
    return Index(nationalities, cities, countries)