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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 nunique(self, axis=0, dropna=True):
 """ Count distinct observations over requested axis. Return Series with number of distinct observations. Can ignore NaN values. .. versionadded:: 0.20.0 Parameters axis : {0 or 'index', 1 or 'columns'}, default 0 The axis to use. 0 or 'index' for row-wise, 1 or 'columns' for column-wise. dropna : bool, default True Don't include NaN in the counts. Returns ------- Series See Also -------- Series.nunique: Method nunique for Series. DataFrame.count: Count non-NA cells for each column or row. Examples -------- A 3 B 1 dtype: int64 0 1 1 2 2 2 dtype: int64 """

        return self.apply(Series.nunique, axis=axis, dropna=dropna)