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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 nlargest(self, n, columns, keep='first'):
 """ Return the first `n` rows ordered by `columns` in descending order. Return the first `n` rows with the largest values in `columns`, in descending order. The columns that are not specified are returned as well, but not used for ordering. This method is equivalent to ``df.sort_values(columns, ascending=False).head(n)``, but more performant. Parameters n : int Number of rows to return. columns : label or list of labels Column label(s) to order by. keep : {'first', 'last', 'all'}, default 'first' Where there are duplicate values: - `first` : prioritize the first occurrence(s) - `last` : prioritize the last occurrence(s) - ``all`` : do not drop any duplicates, even it means selecting more than `n` items. .. versionadded:: 0.24.0 Returns ------- DataFrame The first `n` rows ordered by the given columns in descending order. See Also -------- DataFrame.nsmallest : Return the first `n` rows ordered by `columns` in ascending order. DataFrame.sort_values : Sort DataFrame by the values. DataFrame.head : Return the first `n` rows without re-ordering. Notes ----- This function cannot be used with all column types. For example, when specifying columns with `object` or `category` dtypes, ``TypeError`` is raised. Examples -------- population GDP alpha-2 Italy 59000000 1937894 IT France 65000000 2583560 FR Malta 434000 12011 MT Maldives 434000 4520 MV Brunei 434000 12128 BN Iceland 337000 17036 IS Nauru 11300 182 NR Tuvalu 11300 38 TV Anguilla 11300 311 AI In the following example, we will use ``nlargest`` to select the three rows having the largest values in column "population". population GDP alpha-2 France 65000000 2583560 FR Italy 59000000 1937894 IT Malta 434000 12011 MT When using ``keep='last'``, ties are resolved in reverse order: population GDP alpha-2 France 65000000 2583560 FR Italy 59000000 1937894 IT Brunei 434000 12128 BN When using ``keep='all'``, all duplicate items are maintained: population GDP alpha-2 France 65000000 2583560 FR Italy 59000000 1937894 IT Malta 434000 12011 MT Maldives 434000 4520 MV Brunei 434000 12128 BN To order by the largest values in column "population" and then "GDP", we can specify multiple columns like in the next example. population GDP alpha-2 France 65000000 2583560 FR Italy 59000000 1937894 IT Brunei 434000 12128 BN """

        return algorithms.SelectNFrame(self,
                                       n=n,
                                       keep=keep,
                                       columns=columns).nlargest()