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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 value_counts(self):
 """ Return an SFrame containing counts of unique values. The resulting SFrame will be sorted in descending frequency. Returns ------- out : SFrame An SFrame containing 2 columns : 'value', and 'count'. The SFrame will be sorted in descending order by the column 'count'. See Also -------- SFrame.summary Examples -------- Columns: value	int count	int Rows: 3 Data: +-------+-------+ | value | count | +-------+-------+ | 3 | 7 | | 2 | 4 | | 1 | 2 | +-------+-------+ [3 rows x 2 columns] """

        from .sframe import SFrame as _SFrame
        return _SFrame({'value':self}).groupby('value', {'count':_aggregate.COUNT}).sort('count', ascending=False)